Bug fixes and small performance improvements

Fixes:

• Fixed music not playing on some machines, this fix required going back to an older window backend resulting in your screen setting being reset. Sorry for that

• Fixed so enemies does not try to spawn outside game area in waves mode

• Fixed issue where line enemies spawned bottom formation when they should spawn in top formation

• Fixed bug where the light from the enemies would blink sometimes

• Hopefully reduced stuttering a bit*

• It still stutters sometimes most likely due to garbage collection of allocations I have no practical control over. Tip to aspiring game developers: Don't use Java or C# or any other garbage collected language, it comes with false promises and does not make making games easier.