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
Add Keybase's ExportPrivKey()/ImportPrivKey() API calls to export/import
ASCII-armored private keys. Relevant keys subcommands are provided as well.
Closes: #2020
Federico Kunze
Alessio Treglia
Alexander Bezobchuk