Change the methods available to clarify and improve
Change the methods available to clarify and improve

- pack_state is now to_compact_state
- unpack_state is now to_json_state
- pack_action is now to_compact_action
- unpack_action is now to_json_action
- from_notation parses human-style action input
- to_notation morphs a compact action tuple back into the human-style input

Also, the display method now makes use of the json action and state.

jbradberry/chong