Box dragging

Hitting '3' will select the box dragging ability

Click/drag/releasing a box will move a box in that direction. The speed
is determined by the length of the drag.
Added new ability ("shockwave"), code cleanup

Ability 4: Click and Drag. Upon release, a purple box will appear and
move in the direction of the drag. The purple box emits a force similar
to Ability 2.

Cleaned up other portions of the code (moving sections of code to more
appropriate entities).