New Layer System & refactoring focus

Focus can now be enabled/disabled by pressing F on the keyboard.
You move the camera with Left Mouse Button, you move selected entities
with Right Mouse Button

Layer System is now from 0.00f (Rendered first, background) to 1.00f
(Rendered last, foreground)

HUD has now its own component type so it is renderered last, it's still
possible to use layer for HUD