remove trailing whitespace
fix Plane::transform

Frankly I can not follow the cleverness of the existing code, so this is
now a not-clever version that works ;)
fix QuadTreeTerrain if not located at origin

The frustum needs to be transformed to local (model) coordinates,
otherwise culling tests only work correctly if local == world coords.
remove (unused) assembler shaders
remove dead code (related to assembler shaders), fix indent
handle point lights, use light color in QuadTreeTerrain

Contributed by Christian Bar. Thanks!
fixed: check for missing Image on texture

Fix by Michael Raab.
fixed: check for non-zero number of vertices/indices before draw calls

There are drivers that can not handle this.
Fix by Michael Raab.
fixed: tess control/eval shader mixup

Bug reported by Marcel Weiler.
added: convenience functions for reading tess control/eval shaders
added: image hash

Feature by Michael Raab.
build fix for VS 2013

Reported by Johannes Brunen.
adjust tests for VTK 6
adjust contrib vtk to work with vtk 6

Reported by Johannes Brunen, thanks.
decide at runtime whether to use TexImage3DEXT functions

Prefer the standard functions and fall back to the EXT functions.

Patch by Michael Raab.
fixed: update object dependent procedural shader vars per object
added: OSGViewportSize OSGShaderVariable