Release v4.0.0-alpha.3

[ascjones]

When attempting to release alpha.2, the cargo release auto bumped the version to alpha.3 (see commits in this PR) because I supplied simply alpha as the level instead of the specific version v4.0.0 alpha.2. The result was some crates were published as v4.0.0-alpha.3, with others not being published because the inter-crate dependency versions were not updated.

Version 4.0.0-alpha.3

Breaking Changes

New ink crate

The ink_lang crate has been replaced in #1223 by a new top level ink
crate. All existing sub-crates are reexported and should be used via the new ink crate, so e.g. ink::env instead of
ink_env. Contract authors should now import the top level ink crate instead of the individual crates.

Migration

• In Cargo.toml Replace all individual ink_* crate dependencies with the ink crate.
• In the contract source:
  • Remove the commonly used use ink_lang as ink idiom.
  • Replace all usages of individual crates with reexports, e.g. ink_env ➜ ink::env.

Storage Rework

#1331 changes the way ink! works with contract storage. Storage keys
are generated at compile-time, and user facing abstractions which determine how contract data is laid out in storage
have changed.

Migration

• Initialize Mapping fields with Mapping::default() instead of ink_lang::utils::initialize_contract in
  constructors. See erc20 and other examples which use a Mapping.
• Remove SpreadAllocate, SpreadLayout and PackedLayout implementations.

Removal of wee-alloc support

ink! uses a bump allocator by default, additionally we supported another allocator (wee-alloc)
through a feature flag. wee-alloc is no longer maintained and we removed support for it.

Changed

• Introduce ink entrance crate ‒ #1223
• Use XXH32 instead of sha256 for calculating storage keys ‒ #1393

Fixed

• Trim single whitespace prefix in the metadata docs field ‒ #1385
• Allow pay_with_call to take multiple arguments ‒ #1401

Added

• Add ink_env::pay_with_call! helper macro for off-chain emulation of sending payments with contract message calls ‒ #1379

Removed

• Remove wee-alloc ‒ #1403

[HCastano]

[codecov-commenter]

Codecov Report

Merging #1409 (290856d) into master (6f2beed) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1409      +/-   ##
==========================================
+ Coverage   71.98%   71.99%   +0.01%     
==========================================
  Files         187      187              
  Lines        5953     5953              
==========================================
+ Hits         4285     4286       +1     
+ Misses       1668     1667       -1     

Impacted Files	Coverage Δ
crates/storage/traits/src/impls/mod.rs	0.00% <ø> (ø)
crates/ink/ir/src/ir/attrs.rs	82.27% <0.00%> (+0.27%)	⬆️

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