Made PlayerShotEntityManager.screenDimension final.
Optimized screen redraw.
Moved class Bounds to utils package.
Tweaked entity pool handling.
Tweaked user input to avoid missing fire key press.
Minor engine refactoring.
Hard coded sprite declaration to avoid unnecessary string manipulations.
Removed unnecessary method Entity.reset().
Added player spawn animation.
Removed usage of TreeSet in UserEntityManager.
Very minor Entity tweak.
Added comment in EntityFactory.
Added sprite animation support.
Refactored player shot creation.