- remove circular dependency with fee_schedule
- unitiy build db_* as database.cpp
- move protocol definitions in separate directory
- combined some objects/evaluators
- combined limit/call evaluator/objects into market_evaluator.*
- refactor how signatures are stored on the transaction, removing key_id
and extra_signatures maps and replacing with a vector
- verify that each key only signs one time
- update tests to handle stricter policies on signatures
