Removed Menu lag spikes, added matrix BG!

Hey everyone! In version 1.3.0, I added a new "matrix" and "nothing" BG. The nothing BG is literally nothing.

I also removed lag spikes in the UI by loading the textures earlier.

A cool Idea that my friend had was to make the music dampen when getting a slow-mo item. I think it was a really cool idea, so I put it into the game.