Clean RenderingManager

Make functions more consistent:
The "InitializeView*"-functions basically all do something similar.
They only behave differently in regard to their input parameters.
In order to make the functions more consistent, the following was changed:

• use a function "ExtendGeometryForBoundingBox" to extend the bounding box

	  for all cases where a specific geometry is given
    - use "InternalViewInitialization" in all cases with appropriate arguments

Remove unnecessary includes / comments / namespaces

Add documentation for "InitializeView"-functions