Replaces the janicart with the janitorial cart.

The janitorial cart is everything the janicart was meant to be. It can hold a mop, trashbag, up to four floor signs, a spray bottle, and the light replacer. It is the alpha and omega of sanitation.

Sprites aren't included, Cheri is doing a seperate pull request with them. The icon_states should sync up fine if we're not retarded.

This replaces the janicart on the map, and updates the janitor's starting equipment to not include his keys. It also updates the vault safe.

Finally, it updates the code for the mop and mop bucket, but they should function the same as before.