Multiple Changes

- Camera clamping
- Changed VoxelTerrain to VoxelMap in preparation for ramping up
gameplay elements
- Added zones, still a W.I.P
- Added economy and unit buffs that zones can apply
- Tweaked mouse events to fix some issues with mouse staying pressed
- Tiles can now declare custom methods when added to world
- Fixed some ladder render bugs
- Added a door tile, still a W.I.P