Changes:
- Small cooldown added before energy recovers to make the tail less spamable
- Spawn rate of tails now depends on existing tail density instead of a fixed timer, which makes it a bit more robust for framerate-issues
- Endless Mode is no longer affected by global difficulty setting
- Added option to change scaling quality (mostly for fullscreen)
- Rebalanced the volume of some sounds
- Game does not instantly quit when pressing back/ESC in main menu