Update 1.1 Local Multiplayer update.

Release notes:
- local multiplayer co-op with up to four players
- An additional playable ship
- User interface updates
- Better backwards compatibility for GLES2 capable computers
- A loss of life no longer restarts the level
- Additional ending for the new ship
- Added a lower grade pulse attack, and changed the way the main ship is downgraded when attacked.
- Various bug fixes