Checkpoint Checkin [2 of 2]

Done.
-Controller enforces order of activation
—Sorts by index, starting from index = 0
-Sprites change when activated/deactivated
-Each piece of boxbot now has the tag Player or killable
-Added a circleTrigger to all levels that is the same size as the
canGrab detection
-Uses polygon collider but angles are weird for grabbing

TODO:
-Sign/descriptor for checkpoints
-Switch cangrab detection to circleTrigger (once again splitting the
switchsprite and cangrab up) to use with ontriggerstay