* use BLAKE2b 256-bit hashes for selectors

Before this PR we accidentally used BLAKE2b 512-bit hashing.
Using 256-bit versions is important for smart contracts so that smart contracts can compute selector hashes on their own through the built-in contracts-pallet hash support which includes BLAKE2b 256-bit but not 512-bit.

* apply rustfmt

* [lang/ir] generalize conflicting attribute error reporting

# Conflicts:
#	crates/lang/ir/src/ir/chain_extension.rs

* [lang/macro] add UI tests for payable constructors

* fix docs (review suggestion)

Co-authored-by: Michael Müller <michi@parity.io>

* fix docs (review suggestion)

Co-authored-by: Michael Müller <michi@parity.io>

Co-authored-by: Michael Müller <michi@parity.io>

* add new tests for #[ink(namespace = ..)] and #[ink(selector = ..)] attrs

* [lang] implement new errors for ink! attributes: namespace, selector

* add #[ink(extension = N: u32)] attribute

* apply rustfmt

* [lang] add initial implementation of chain extension proc. macro

* [lang] rename AttributeArg -> AttributeFrag

* rename AttributeFrag::kind field to arg

* rename AttributeArgKind -> AttributeArg

Also introduce a new AttributeArgKind type and AttributeArg::kind method.

* [lang] apply rustfmt

* add Display impl for AttributeArgKind

* [lang] use AttributeArgKind in sanitize_attributes and ensure_first methods

* [lang/ir] improve error reporting for duplicate ink! attributes

* [lang/ir] refactoring and improvements to chain extension IR impl

* [lang/ir] add tests for IR implementation of chain extensions

* [lang/ir] remove some code dupe

* [lang/ir] add getters to ChainExtension

* [lang/ir] add re-exports for ChainExtension definitions

* [lang/codegen] add initial impl for ChainExtensions

* [env] add ChainExtension assoc type to the Environment trait

* [lang] initial impl to make it possible to use chain extension syntax

* [env] improvements to chain extensions API

Also removes the unstable crate feature guarding the feature.

* [lang/macro] add UI test for chain extension

* [lang/macro] register new UI test

* [lang/codegen] fix some codegen bugs with new chain extension feature

* [lang, env] apply rustfmt

* [lang/ir] apply clippy suggestions and fix outdated error messages

* [lang/ir] fix some tests and incorrect error messages

* [examples] apply clippy suggestion

* add ErrorCode to ink! chain extension trait

* add FromStatusCode trait to ink_lang

* add #[ink(expect_output)] and #[ink(expect_ok)] attributes

Also add their handling for the #[ink::chain_extension] proc. macro.

* add ink_lang::IsResultType trait

* add ChainExtensionMethodInputs iterator

* hide docs for IsResultType trait

* add some docs to chain extension codegen

* implement expect_ok and expect_output where bounds in codegen

* apply code review suggestions by (cmichi)

* add ReturnCode::into_u32 getter

* change return type of ext::call_chain_extension: RetCode -> u32

Chain extensions do not follow the general scheme of error return code because they have their own set of errors that is custom defined by the author of the chain extension.

* [lang] add ChainExtension trait

Not yet sure we need it.

* change EnvBackend::call_chain_extension signature

The new signature is much more low-level and supports all the different ways to call a chain extension method.
This commit already implements the chain extension call on the on-chain environment.
More work needs to be done to properly support this for the off-chain environment.

* remove old high-level API for calling chain extension methods

* [env] add new high-level module to handle chain extension calls

* rename ChainExtensionMethodInstance -> ChainExtensionMethod

* [env] add doc examples to chain extension method API

* apply rustfmt

* [env] clippy: allow complex type in ChainExtensionMethod type state

* silence some warnings

* re-export IsResultType from ink_lang crate

* [lang] remove FromStatusCode trait

This trait already exists in the ink_env crate.

* [lang] update codegen for chain extensions

Not yet done but close.

* [lang] update simple chain extension test

Compiles now again.

* apply rustfmt

* update some license headers

* [env] fix where bound

* extend chain extension test case to cover all cases

* add messages for read_small, access and unlock_access

* fix some bugs with chain extension method signatures in test

* fix some bugs and docs in chain extension test

* fix test

* update quickcheck to 1.0

* [env] implement chain extension calling for off-chain env

The new interface is much more lower-level and it is still impossible to use chain state from within the chain extension call. The latter must be fixed as soon as the off-chain environment receives its rework.

* apply rustfmt

* add docs to #[ink::chain_extension] proc. macro

* rename env_types -> env everywhere

* make doc examples for #[ink::chain_extension] compile

* add yet another technical limitation

* make link to simple.rs test case more stable (point to revision)

* fix docs (code suggestion)

Co-authored-by: Michael Müller <michi@parity.io>

* fix docs (code suggestion)

Co-authored-by: Michael Müller <michi@parity.io>

* fix docs (code suggestion)

Co-authored-by: Michael Müller <michi@parity.io>

* fix docs (code suggestion)

Co-authored-by: Michael Müller <michi@parity.io>

* add dev. note to Backend::call_chain_extension

* fix docs example (code suggestion)

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* [env] chain extension: make doc examples/tests compile

* fix some doc comments according to review suggestions

* review suggestion: telling -> meaning

* fix docs (review suggestion)

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* fix docs (review suggestion)

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* improve docs (review suggestion)

Co-authored-by: Andrew Jones <ascjones@gmail.com>

* rename chain extension test file

* analyse_error_code add doc comments for possible errors

* rename expect_ok -> returns_result and expect_output -> handle_status

Some examples and docs might be invalidated or outdated.

* [lang/ir] improve error reporting for ink! namespace attribute with missing parameter

* [lang/*] implement new handle_status and returns_result attributes

* [env] apply rustfmt

Co-authored-by: Michael Müller <michi@parity.io>
Co-authored-by: Andrew Jones <ascjones@gmail.com>

* Fix typo

* Fn does not need to take mutable self

* Fix naming: #[ink(implemenetation)] ➜ #[ink(impl)]

* #[ink(storage)] can not be applied to enum

* Fix typo: accesses ➜ accessed

* Fix typo: sturctures ➜ structures

* [lang] Improve invalid selector message

* [lang] Improve span

* [lang] Return syn::Error instead of panicking

* Make clippy happy

* [lang] Reduce code dup with non_hex_err

* [lang] Rename fn

* [lang] Fix err functions

* [lang] Add comments

* [lang] Remove unnecessary lifetime

* [chores] Fix typo: invokation ➜ invocation

* [chores] Fix typo: timstamp ➜ timestamp

* [chores] Fix typo: ininitialized ➜ initialized

* [env] Implement terminate_contract in off-chain env

* [examples] Add lock-until

* [env] Implement proper off-chain testing for ext_terminate

* Apply suggestions from code review

Co-authored-by: Hero Bird <robin.freyler@gmail.com>

* [env] Fix Environment type

* [env] Derive Balance/AccountId from Environment

* [env] Fix types in macro

* [examples] Remove lock-until

* [examples] Add contract-terminate

* [examples] Add contract-transfer

* [examples] Make clippy happy

* [examples] Fix example name

* [examples] Remove Default impls

* [examples] Move macro to contract-terminate/test_utils

* [env] Migrate macro to fn which gets Environment type param

* [env] Add explanatory dev comment

* [examples] Allow clippy::new_without_default

Co-authored-by: Hero Bird <robin.freyler@gmail.com>

* [env] rename Env -> EnvBackend, TypedEnv -> TypedEnvBackend

* [env] rename EnvError -> Error

* [*] rename ink_env::EnvTypes -> Environment

Namely rename:
ink_env::EnvTypes -> Environment
ink_env::DefaultEnvTypes -> DefaultEnvironment

* [*] update cfg-if dependency 0.1 -> 1.0

* [alloc] rename ink_alloc -> ink_allocator

* [env] forgot to rename in lib.rs

* [env, lang] fix some bugs with ink_env::EnvError -> Error renaming

* [ci] adjust renaming of ink_alloc -> ink_allocator

* [env] apply rustfmt

* [lang/macro] re-enable disabled UI test

* [examples] DNS: apply rustfmt

* [examples] ERC-20, ERC-721: apply rustfmt

* [env] remove unnecessary copy of no longer used mod.rs

* [env, lang] make crates compile again under newest Rust nightly

* [env] on-chain: enhance ScopedBuffer

Add append_encoded and take_appended methods.

* [env] remove old Topics trait

* [env] add new Topics infrastructure

* [env] implement new Topics infrastructure for on/off chain environments

* [env] remove dummy event

* [env] make env::topics::state mod externally accessible

It stays hidden in docs.

* [lang/codegen] generate proper Topics impls for ink! events

* [env] apply rustfmt

* [lang/codegen] fix codegen for events without topics

* [lang/macro] fix UI test

* [env] off-chain: clean-up slightly

* [examples] ERC-20: improve tests for event topics

* [env] remove commented-out line

* [lang/codegen] include event signature into topics

This is the same as it is done for non-anonymous Solidity events.
The signature of an ink! event is: ContractName::EventName.
E.g. for ERC-20's Transfer event it is: Erc20::Transfer

* [examples] ERC-20: adjust test for changes with event topics

* [lang/ir] add support for anonymous events

* [lang/codegen] add codegen for anonymous events

* [lang/ir] apply rustfmt

* [lang/macro] comment out failing unit test

Fails due to rustc version mismatch and some recent error display change.

* [examples] apply rustfmt

* [*] split ink_core into ink_env and ink_storage

The workspace does not yet compile!

* [env] make compile again

* [env] fix doc tests

* [storage] make crate compile again

* [env] fix some doc comment links

* [README] flipper example: remove unused import

* [storage/derive] fix compilation of generated code

* [README] add ink_storage and ink_env doc links

* [env, primitives, storage] fix docs

* [lang] make compile again

* [lang/codegen] use absolute paths in #[ink::test] proc. macro

* [examples] make compile again

* [*] apply rustfmt

* [env] remove unneeded dependencies

* [storage] remove all unneeded dependencies and crate features

* [*] update outdated dependencies

* [env, lang] remove unused dependencies

* [*] fix comments

* [*] fix some intra doc links

* [ci] adjust to split ink_env and ink_storage crates

* [ci] forgot to handle split ink_env and ink_storage in docs

* [storage] fix fuzz tests

* [examples] apply rustfmt

* [examples] apply rustfmt (ERC-721)

* [chores] update README to new ink! 3.0 syntax

* [*] update all broken LICENSE and README.md symbolic links

* [*] update all license headers

Also be more strict about their dates: 2018-2020 for all

* [*] move all ink! crates into crates/ directory

* [ci] adjust .gitab-ci.yml to crates/ directory

* [ci] fix GitLab .gitlab-ci.yml (attempt #2)

* [ci] forgot some lines in attempt #2

* [examples] fix example smart contracts

They need to readjust their paths for the crates/ directory.