BUGFIX: Fixed an issue where build menu button colors were not updating correctly
Balance updates
- Tank nerfed to 45 hp
- Sniper armor increased form 0 to 1
Nerfed snipers back to 0 armor
Added stealth mode

- TODO don't dim squares when moving if invisible
- TODO don't allow selection/attack if invisible
- TODO only allowed 1 move / turn when in stealth
Can no longer select enemy cloaked units
Cloaked units can no longer be attacked
Movement speed decreased to 0.5x when in stealth mode
Attacking now brings unit out of stealth

Can now select units when in stealth mode
Incremented version to 9
Marines now have "detect" ability allowing them to shoot cloaked snipers
BUGFIX: Surrender was only working in single player
Balance changes
- marines back to 3 range
- snipers cost 100
- saboteurs cost 75
BUGFIX: Refund amounts display properly
Implemented collidable and traversable for TileLayer

- collidable tile layers describe blocking tiles that cannot be traversed
- traversable tile layers define where units can move
Implemented a bloom-filter-like algorithm to determine vision

- Theoretically faster than old method (old was O(units * mapsquares), this should be more on the order of O(units * log(mapsquares) or something)
Movement highlight now uses bloom-filter method
Movement validation now uses bloom filter

- still need to add a check that a tile is traversible and not blocked
Can't jump across non-traversible places, but can see across
Increment version to 10; nightly build
Moved assets to "local" rather than "internal"