Fourth Background Layer

Will: Slime_Cubed's fourth layer mod was added late into development.
Originally, the fourth layer was something cut from Rain World's base game.

Will: It was later restored with this mod, but lacked content to make use of
it. If we were going to add this mod, we should at least present its use!

Will: As such, every region with enough background space for a presentable
fourth layer was given its own unique background screens to use.

Will: Most of these new layers are uniquely made rooms being projected
behind the normal room layers, but some are unique art made in other ways.

Will: Regardless, I'd call our showcase of MSC's built-in forth layer support,
to at least be somewhat of a success! Most of the rooms I did were based off
of the old alpha version! Or contain specific references to features from it.