Music and Combat Rework!

Due to popular opinion, combat has been reworked.

There is no longer a significant charge time - your attack charges instantly. You can hold onto the attack for a short period like before, but if you want an instant strike, you've got an instant strike!

A single music track has been added, and loops in the background. Likewise, there are now volume controls in the in-game settings.

Turrets and projectiles have been reworked. More bullets, less projectile speed. Should make things way more exciting!

Levels have been cleaned up a bit, and all 5 should be good to go without any major issues.

A ton of small bugfixes, as expected.