* Make `decl_error!` errors usable

This pr implements support for returning errors of different pallets in
a pallet. These errors need to be declared with `decl_error!`.

The pr changes the following:

- Each dispatchable function now returns a `DispatchResult` which is an
alias for `Result<(), DispatchError>`.
- `DispatchError` is an enum that has 4 variants:
  - `Other`: For storing string error messages
  - `CannotLookup`: Variant that is returned when something returns a
  `sp_runtime::LookupError`
  - `BadOrigin`: Variant that is returned for any kind of bad origin
  - `Module`: The error of a specific module. Contains the `index`,
  `error` and the `message`. The index is the index of the module in
  `construct_runtime!`. `error` is the index of the error in the error
  enum declared by `decl_error!`. `message` is the message to the error
  variant (this will not be encoded).
- `construct_runtime!` now creates a new struct `ModuleToIndex`. This
struct implements the trait `ModuleToIndex`.
- `frame_system::Trait` has a new associated type: `ModuleToIndex` that
expects the `ModuleToIndex` generated by `construct_runtime!`.
- All error strings returned in any module are being converted now to `DispatchError`.
- `BadOrigin` is the default error returned by any type that implements `EnsureOrigin`.

* Fix frame system benchmarks

pallet-evm: default implementation for FeeCalculator and ConvertAccountId and separate gas price (#4424)

* Default implementation for FeeCalculator and ConvertAccountId and separate gas price

* Styling fixes and some docs addition

* TruncateConvertAccountId -> HashTruncateConvertAccountId

* Fix compile

* Update assets to `decl_error`

* Update aura to `decl_error`

* Update authority discovery to `decl_error`

* Update collective to `decl_error`

* Update evm to `decl_error!`

* Fix error with replace

* Revert "Update authority discovery to `decl_error`"

This reverts commit 26e8f3c5.

* Revert "Update aura to `decl_error`"

This reverts commit 8f17c44c.

* Update democracy to `decl_error`

* Update finality-tracker to `decl_error`

* Update grandpa to `decl_error`

* `assert` to `ensure` in dispatchable function

* Rename: Phase 1.

* Unify codec.

* Fixing: Phase 2

* Fixing: Phase 3.

* Fixing: Phase 4.

* Fixing: Phase 5.

* Fixing: Phase 6.

* Fixing: Phase 7.

* Fixing: Phase 8. Tests

* Fixing: Phase 9. Tests!!!

* Fixing: Phase 10. Moar tests!

* Finally done!

* More fixes.

* Rename primitives:: to sp_core::

* Apply renames in finality-grandpa.

* Fix benches.

* Fix benches 2.

* Revert node-template.

* Fix frame-system in our modules.

* Remove warnings when compiling runtime.

* Remove dispatch::Result imports.

* Add missing imports.

* Fix missing vecs. #4333

* Fix oom function.

* Remove superfluous import.

* More warnings.

* primitives/sr-std -> primitives/std

* fix

* fix conflict

* rstd -> sp-std

* git mv

* fix review

* fix merge

* pallet-evm: weight calculation for call/create based on gas provided

* Update frame/evm/src/lib.rs

Co-Authored-By: Niklas Adolfsson <[email protected]>

* Adding script for rename, could be applicable for nodes on top of it, too

* add stderr and gitlab ci features

* apply script

* fix now minor details in expected stderr

* Update the Cargo.lock

* fix name: sc-transaction -> sc-tracing

* fix rename in script, too

* palette -> frame

* PALETTE, Palette -> FRAME

* Move folder pallete -> frame

* Update docs/Structure.adoc

Co-Authored-By: Benjamin Kampmann <[email protected]>

* Update docs/README.adoc

Co-Authored-By: Benjamin Kampmann <[email protected]>

* Update README.adoc

* Fisr migrated version of weight to paint

* Bump

* Minor nits

* Some review fixes.

* Line width

* Revert spec bump

* Fix build

* Update lock file

* Update palette/executive/src/lib.rs

Co-Authored-By: Bastian Köcher <[email protected]>

* Update palette/membership/src/lib.rs

Co-Authored-By: Bastian Köcher <[email protected]>

* /paint to /palette

* rename paint to palette

* rename the modules in palette to be pallets

* update Structure.adoc

* bump impl

* fix CI directory

* Update docs/Structure.adoc

Co-Authored-By: Benjamin Kampmann <[email protected]>

* Adding first rough ouline of the repository structure

* Remove old CI stuff

* add title

* formatting fixes

* move node-exits job's script to scripts dir

* Move docs into subdir

* move to bin

* move maintainence scripts, configs and helpers into its own dir

* add .local to ignore

* move core->client

* start up 'test' area

* move test client

* move test runtime

* make test move compile

* Add dependencies rule enforcement.

* Fix indexing.

* Update docs to reflect latest changes

* Moving /srml->/paint

* update docs

* move client/sr-* -> primitives/

* clean old readme

* remove old broken code in rhd

* update lock

* Step 1.

* starting to untangle client

* Fix after merge.

* start splitting out client interfaces

* move children and blockchain interfaces

* Move trie and state-machine to primitives.

* Fix WASM builds.

* fixing broken imports

* more interfac...

* srml-evm: init the basic structures

* srml-evm: finish executor implementation

* srml-evm: implement balance deposit and withdraw

* srml-evm: implement the actuall call/create

* srml-evm: use crates.io version of evm

* srml-evm: fix no-std compile

* Remove dependency patch

* Update to evm 0.14

* Use double map for account storage

* Add precompiles support

* Add some basic docs

* Use runtime_io::chain_id()

* Update srml/evm/src/lib.rs

Co-Authored-By: Xiliang Chen <[email protected]>

* Update srml/evm/src/lib.rs

Co-Authored-By: Xiliang Chen <[email protected]>

* Fix WithdrawReason

* Unique saturate balance to u128

* Unique saturate withdraw to u128

* Remove extern crate alloc

* Move account code to a separate storage and use ref for convert_account_id

* More match cause for error message

* Fix potential interger overflow

* Use decode_len for fetching code length