Implements JSTilemap functionality.
- Adds bounds checking for turning. Since the new tileset contains some “non-road” areas of the road tiles, we need to set up a bounding box to check to see if the target point is within the road bounds.
Refactors authorizeTurnEvent; adds DEBUG preprocessing macro to enable bounding box visibility

TODO: Use CGPaths instead of Sprite Nodes for bounds detection in authorizeTurnEvent
Implements CGPath bounds
Extends CGPath-based turn authorization
Implements path boundaries for all road tiles.

TODO: Less strict window for when the user can execute a turn; handle situations where the car is forced to turn even without user intervention (e.g. T-intersection or corner)
Ignore .xccheckout files
Merge branch 'jstilemap'