Fixed Collisions, Added Collision Logs, New Bikes

+Fixed Collisions
>Added a ton of continues to the resolveConfilcts() method, so that you
dont record two crashes for the same Bike
>Cleaned up proposedMove() method; made sure that you cant have
non-right angle directions
>Changed all grid.put() and grid.remove() in TronWorld to put() and
remove() - better practice
>Overwrote isValid() method in TronGrid to account for null Locations
>Trails are created even when you crash

+Collision Logs
>Yellow brick says what place you get when you crash
>System.out.println crashes and Step counter

+New Bikes
>Constant Bike (drives in a straight line)
>Random Bike (you can figure this one out)
>Removed simple constructors for Bike (now you have to specify grid,
name, and color)