New Signature interface available in the top level types package.
auth.StdSignature implements such interface. User defined auth
module can now define their own custom signature types.
Work carried out in the context of the following issues:
- #4488
- #4487
Refactor
* No more decorators, but rather types.AntiHandler
* No more handlers, but rather types.MsgHandler
* Ability to pass "stores" in NewXYZHandler()
* Coins live in types, and Accounts have coins
* Coinstore -> bank
Alexander Bezobchuk
Alessio Treglia
Dev Ojha
Jae Kwon