Refactored spec reading, added int type default, updated tests.
Added tests for binary reading. Flags are now a one-width bitfield.
Refactored all binary operations to use bitstring module.

So, bitstring is now a dependency. Yay. But it will do the job I
need, better than what I was putting together myself.

TableEntries have been reclassified as RomStructs, and will be the
basic object read from roms.