* The "Use Key" (Q or Spacebar) now activates the Warp Door instead of a
collision event doing so.
* Warp Doors are now functional: the player opens a door, disappears,
the door closes; player is teleported to the linked door which opens,
appears the player and closes.
* If the player exits thru a Blue or Orange door which is disabled
(dotted outline), the door still opens and drops the player off but
returns to a Disabled state, acting as a one-way door.
* Clean up several debug log lines from Doodle and doodad scripts.
* Take advantage of the new Window Manager feature of the UI toolkit.
* Move the MenuScene's "New Level" and "Play/Edit Level" windows into
stand-alone functions in new pkg/windows/ package. The 'windows'
package is isolated from the rest of Doodle and communicates using
config variables and callback functions to avoid circular dependency.
* MenuScene calls the window constructors from the new package.
* Add an "Options" button to the Menu Bar in the Editor Scene, which
opens the "New Level" window to allow changing the wallpaper or
bounding type of the level currently being edited.
* Move the cheat codes into their own file, cheats.go
