PHYS-13 #time 25m #comment Got BillProperties moved out of main and converted to a standalone class.
PHYS-16 #time 10m #comment Minor cleanup in ShapeList.
PHYS-1 #time 1h 30m #comment Got Quadrant appropriately calculating all forces inside it. YES YES YES YESSSS!!!!!! Also, a few other minor refactorings. Most importantly, I got rid of the overriding mass methods in the Quadrant class.