Major refactor for 2.0.0 final

- #14: Refactor packet read/write
- #10: Refactor GameMessagePacket
- #7: Remove all "magic numbers" from the code
- #5: NPC captain personality or ship modifiers unavailable (new
IntelPacket)
- Fixed issues with fields 4.4 - 4.7 and 6.5 - 6.7 of NpcUpdatePacket
- WelcomePacket and VersionPacket are now explicit types for which
clients can listen
- All packets extend BaseArtemisPacket now (reduces code repetition)
- Unified toString() handling for packets and objects
- All world objects can now produce a SortedMap of their properties
(useful for debugging)
- Created new Artemis class to provide a central location for
game-related constants
- Improved code formatting in numerous locations
- Removed some testing/debugging classes that were too dependent on the
old way of doing things; new stuff will be written to replace it