Milestone 3 and Code Refractor

Change List:

Code Refractored - Code for updates and methods moved into their
allocated classes out of App.Main

State Engine added: Level implementations added with possibility to add
game menus

Projectile Bug Fix: Fixed all bugs with projectiles not being able to
despawn and added a few lines to make sure they despawn ON the walls,
not after them.

General Code clean and streamlining: Fixed a few areas of code that were
not needed and slimlined a few methods down to a few lines.

General Code Improvements

Projectile Sprite: Added a sprite for the projectile, needs fully
implementing