* The colored locked doors and the Electric Door are increased in size
to better match Boy's sprite size.
* Colored doors now have a "locked" and "unlocked" state when closed;
when locked, a gold padlock hangs on the door with a keyhole shaped to
match the corresponding Colored Key.
* Revamped the sprites for the four colored locked doors. They now have
a side-view profile perspective rather than a front view.
* Doors open facing the left or the right based on what direction the
colliding actor approached it from.
