* switch to amino for SignBytes and add Reply with error message
- currently only Vote is done
* switch Reply type in socket for other messages
- add error description on error
* add TODOs regarding error handling
* address comments from peer review session (thx @xla)
- contains all changes besides the test-coverage / error'ing branches
* increase test coverage:
- add tests for each newly introduced error'ing code path
* return error if received wrong response
* add test for wrong response branches (ErrUnexpectedResponse)
* update CHANGELOG_PENDING and related documentation (spec)
* fix typo: s/CanonicallockID/CanonicalBlockID
* fixes from review
Ismail Khoffi