Level switching

Added a bunch to start the level-switching capability
Each level now has a 0-indexed identifier to be compatible with arrays I
made
The arrays include the paths for the level's tile and objects, the
starting x and y offsets, and whether you finished the level or not
When you're near an "elevator" (I made chairs elevators for lack of an
actual elevator raisedobject), a popup shows telling you that you can
press x or space to continue or go to the first level