Began to make it possible for many obstacles

Started writing arraylist code so that many objects can be added to an
arraylist of all objects and cars in the game. This is a bit problematic
since each object now needs to know its scale. It cannot be hardcoded as
is (unless other changes are made). This code is commented out just
after the originial collision detection code.
Furthermore, collision now works in Singleplayer. It did not work
previously because the collision detection code was in multiplayer-only
code.
Imported System.Collections* rather than System.Collections.Generic to
access array list.