Fixed slowdown in ParticleEngine
Parallel optimization in ParticleEngine update loop (now works fine with ~4000 particles)
Merge branch 'master' of https://github.com/TDT4240-Exercises/TDT4240-Project

Conflicts:
	x2-gameproject/x2-gameproject/x2-gameproject/GameInstance.cs
	x2-gameproject/x2-gameproject/x2-gameproject/MainMenuState.cs