* Make use of StorageHasher and HasherKind.
* Use Storagehasher hasher function for key2 of double map.
* Refactor to reuse hasher from implementation.
* Bump up since there is srml changes.
* Update metadata version.
* factorization
* introduce GenericUnhashedStorage
* implement generator and storage
* impl double map in storage macro
* improve StorageDoubleMapXX methods
* remove storage from example and impl test
* remove old comments
* wasm compatible
* improve imports
* rename storages
* update runtime impl version
* make code less verbose
* impl hash config for second key in double map
hash available are all of Hashable trait
* use double map in decl_storage for contract
* fix double map config issue
* add hasher into metadata
* update impl version and build wasm
* doc
* add attrs
* update metadata version
* update runtime version
* fix unused storage
* Support skipping the interactive purge prompt
Skip it via `cargo run -- purge-chain -y`.
* Fix typos
* Add Grandpa telemetry
* Address comments
* Revert unnecessary version bump
* Version bump to make CI run
* Remove unnecessary cast
* Do not bump version
kaichao