Added a way to earn powerups.

There is now a store in the main menu where you can exchange Stars for Powerups. The more you buy the better discount you get. I then set up a reward system, so if it's your first time finishing a level you get up to 3 stars, and I can later add levels that give powerups as a reward as well. This ended up being quite the overhaul of the main menu and a lot of background systems.

While I was redesigning the main menu, I didn't want it to be too data heavy, and wanted to show something representative of the game itself, so I added some animation in the form of a big blob of balls that move around and change sizes in a cool way. Secret Tip: It responds to dragging.