Minor Adjustments

Ok, so I've added a main menu and made it so the sensitivity and volume are saved across scenes. I also removed the recoil from the revolver because it doesn't really make sense, originally it was sort of a mobility feature where you could get to higher up places faster at the cost of the long reload time. But that doesn't make much sense anymore now that you can walk on the ceiling. Speaking of the ceiling the lava actually works now, but there's a bug where you get stuck if you touch the inner wall of the pit. Another thing im looking at fixing is the way sensitivity is handled, right now its constant across every frame. So at higher framerates it goes faster and at slower framerates it goes slower. And also there's this thing with aspect ratios that I'm not really sure how to fix but I'll cross that bridge when i get to it.