- Added some debugging code to find a bug with the pathfinder.
- Fixed an issue where the pathfinder was sometimes ignoring the need to
  recalculate the path when the lastMovementTime was bigger than the max
  update time.
- Added code to detect when a path has a length of 0 when running
  followPath.
Added code for the button object and tested it.
Fixed some bugs with the way the navigationTiles were being cleaned up.