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
Gaia is removed from cosmos-sdk repository.
Few changes were required to make sure no packages depend on gaia subpackages.
CI config is amended accordingly.
Unnecessary targets are removed from Makefile.
Simulations run through a lightweight version of gaia renamed to simapp.
Closes: #4104
Alexander Bezobchuk
Alessio Treglia