Renderers and ortho projection

[reinago]

Renderers that currently fetch intrinsics from the camera to get hold of the near plane, for example, will not work (exception) when view is set to ortho. The SphereRenderer suffers from this, for example. Solution: fetch the near plane directly
this->curCamNearClip = cam.get<core::view::Camera::NearPlane>();
as this automatically work regardless of the type of projection.

TODO: check all renderers, basically.