Started on multi-level infrastructure
Updated level ending messages
Added level transition, fixed overlays
Updated TODO
Windows Phone touch support
Initial level transitions
Completed level transitions
Merge branch 'levels'
Added gnat
Initial work on tank
Most of tank guns
Completed tank weapons
Finish tank enemy
Updated TODO
Initial work on second boss
Second boss weapons
Updated TODO
Finished first boss
Fix first level
Added shorter, easier first level