Contract accounting removal (#2230)

* first partial implementation

* update rent allowance

* fmt

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* remove comments

* reward surcharge claims

* remove rent allowance in param + code_hash changed

* Fix bug

* fix tests

* fmt

* impl getter setter rent allowance

* fmt

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* comments

* doc + be->le

* doc

* doc

* fix improve fast return

* renamings

* rename + COMPLEXITY

* COMPLEXITY

* add test

* etrinsic claim surcharge delay configurable

* comment addressed

* move and rewrite of pay_rent

* remove child trie

* fmt

* use derive

* arithmetic operation

* fix

* fix storage root + checked_mul + test

* WIP: test

* WIP

* add tests and fix

* fmt

* typo and doc suggestions

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

* WIP

* address some comments

divide tests + some docs

* use br_table

* remove unused function

* Bump the runtime version

* insert_with

* Add some comments.

* Refactor

* Shuffle and fix comments

* More comment fixes.

* dues limited

* Add comment

* Handicap

* Docs.

* Apply suggestions from code review

Co-Authored-By: pepyakin <s.pepyakin@gmail.com>

* Coalesce block_passed in a block

* Fix build

* Paid → Ok

* match → if

* Imrpove handicap description

substrate/core/state-machine/src/testing.rs

@@ -159,7 +159,7 @@ impl<H: Hasher> Externalities<H> for TestExternalities<H> where H::Out: Ord + He
 	}
 
 	fn child_storage_root(&mut self, _storage_key: ChildStorageKey<H>) -> Vec<u8> {
-		unimplemented!()
+		vec![]
 	}
 
 	fn storage_changes_root(&mut self, parent: H::Out, parent_num: u64) -> Option<H::Out> {