moving the rest of the consensus tests to gocheck
adding lock to preaccept message sending
removing test obsoleted by status change idempotence
adding tests around sent message ballot failures, and removing some todos
updating add missing instances, and implementing test around it
implementing handle prepare message method
add missing instance support and tests to preaccept response handling
testing commit count and execute timeout
moving execute instance into a mockable var function
adding async execute and test to commit
turns out, I was using the cond object wrong
implementing the execute instance prepare logic and tests
adding test around updating instance ballots from prepare responses
adding errors and utils to the message package
moving message utils into the serializer package
adding instance serialization implementations
gocheckifying instance tests
implementing instance serialization/deserialization and supporting tests
making some general purpose message serializer/deserializers that can be used by multiple packages
adding serialization and tests for the preaccept messages