* Unify error enums in substrate and ethereum clients with `thiserror`

Related to https://github.com/paritytech/parity-bridges-common/issues/857

* Add license pre-amble

* rustfmt

* Fix spelling

* Alter gitlab.

* Use substrate's rustfmt.toml

* cargo +nightly fmt --all

* Fix spellcheck.

* cargo +nightly fmt --all

* format.

* Fix spellcheck and fmt

* fmt?

* Fix spellcheck

Co-authored-by: Tomasz Drwięga <[email protected]>

* box large arguments

* benchmarks

* fix

* move some associated types from relay_substrate_client::Chain to bp_runtime::Chain

* dummy commit

* Revert "dummy commit"

This reverts commit 81bc64aa.

* I'm just trying to do my job

* spelling

* fix delivery transaction estimation in greedy relayer

* fixed typo

* improve logging

* improve logging

* fmt

* fix compilation

* fmt

* Update relays/lib-substrate-relay/src/messages_target.rs

Co-authored-by: Tomasz Drwięga <[email protected]>

* review

Co-authored-by: Tomasz Drwięga <[email protected]>

* Remove redundant generic parameters from SubstrateMessagesSource

* Remove redundant generic parameters from SubstrateMessagesTarget

* use uniform alias naming

* use aliases instead of fully quallified syntax

* pr feedback

* mortal relay transactions

* sign block hash for mortal transactions

* TransactionEraOf

* add explanation

* enable mortal transactions for Westend -> Millau headers relay

* clippy

* spellcheck

* remove unused dev deps

* Removing unused deps

* update conversion rate: initial commit

* Rialto=Polkadot && Millau=Kusama + actually update conversion rates

* update deployment scripts and readme

* allow non-zero difference between stored and real rates

* dummy commit

* Revert "dummy commit"

This reverts commit a4381981.

* clippy

* #[allow(clippy::float_cmp)] in conversion rate update

* dummy

* Revert "dummy"

This reverts commit 90cd6e47.

* spell

* shared_value_ref() -> get()

* Revert "shared_value_ref() -> get()"

This reverts commit 20aa30de.

* get rid of frame_support::traits::Instance usage in messaging

* migrate messages pallet to frame v2

* fix benchmarks

* remove dummy event + add Parameter to metadata

* review

* typo

* added missing docs

* added .cargo to gitignore

* lib-substrate-relay

* pass to build

* remove unused file

* clippy && tests

* Changed follow suggestions

* License

* Make changes follow suggested

* docs

* fix fmt