Player is now a Game argument
Implemented regen, plus several bug fixes
- Fixed bug where BattleComponent doesn't call super() (can't send events)
- Fixed bug where level-up triggers on every experience gain
- Regen event is only added if you have a regen_percent
- Fixed bug where event system is not intialized properly
- Fixed bug where tags (not components) get `receive_event`
- Implemented health regen