Bug fixes and small performance improvements — Dextram Steam update #1016842

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.