Dunno what happened, but I don't have time to fix it right now.

Fix the stuff that broke in merge.

Also remove transaction_evaluation_state and the size_checker program.

- Cleaned out some cruft
- Added some new macros to remove boilerplate
- Added some more test cases

Add a testing_network class to emulate a P2P network ferrying blocks
between databases.

Add some test cases exercising databases syncing with the
testing_network and resolving forks.