Improves shadow mapping and adds some other minor tweaks and fixes.

* Adds that the shadow/light camera is moved in steps of texels (this fixes the flickering of the shadows when moving around in the world)
* Makes the size of the shadow map configurable via the config file
* Makes the amount of chunks used for shadow rendering available in the config available
* Removes that alpha reject objects in the scene get sorted by the distance to the camera (which is absolutely not necessary)
* Adds that the inverse view projection matrix is calculated in the Orthographic camera class