Extends and cleans up Terasology's runtime debugging and debug rendering capabilities and adds a new debug shader for displaying various rendering stages. Also...

* Renames PostProcessingRenderer to DefaultRenderingProcess
* Moves block hint defines from the shader as an enum to the Application code base where they get "dynamically" added as defines during shader compile time
* Moves "wireframe" setting from the WorldRenderer to the SystemConfig class
* Adds that F8 can be used to toggle the AABB rendering of chunks (debug mode only)
* Adds the possibility to hide the first person view via a SystemConfig setting
* Adds that the H key also hides the first person view (debug mode only)