Update: Upgrads and Persistent Stats

Going the path of a rougelike, your health and such need to be persistent from fight to fight. So that's what this includes.

- Whenever a session is started, you are initialized with a fixed amount of Health, Attacks, Damage, and Attack Regen rate.
- After each victory you may choose (with literally no limit in the current implementation, as of 4-15-2020) an upgrade to modify your stats. These stats remain until you die, or you restart the game.

There's also an additional difficulty change, wherein I've made it so that the rotation speed of the obstacles increase as the enemy gets closer to death. A Rage mode that intensifies the closer you are to winning, as it were.