Bug 1485

Pixel accurate clipping of the rendered Region is essential 
for GraphUI, allowing to pixel accurate cut-off an inner Region 
using its parent Group's AABBox (outside).

Object culling beforehand is possible to enhance performance (TODO) inside a Group,
this on top of frustum culling from the Scene.

- Graph GLSL functions.glsl: Complete overload vec2 and vec3 variants;
  Fix 'and'/'or' semantic (swapped); Add EPSILON in clip_coord(..)
  and add is_inside(..) function
  commit c87e89959e40ee8411cccc16fe0a5708f54a6c9f

- Graph Clipping: GLSL: Add `USE_AABBOX_CLIPPING`, 
  i.e. clipping via AABBox min/max vec3 as convenient 
  using Graph/GraphUI produced AABBox
  commit f836fbd9201034010ecbf591348433f23920f527

- Graph Clipping: Initial Region impl of AABBox clipping 
  using GLSL shader (Convenient using Graph/GraphUI produced AABBox)
  commit bb11c498b7d4fe269e7273a1b164e46f3c7a3b50

- Graph Clipping: Add missing Modelview-Matrix (Mv) Multiplication / Consideration
  commit 335dd0a493fff1435cad1cd22e4ac5a20d7df03a

- Graph/GraphUI: Revise Graph Region ShaderMapping, 
  fix AABBox-Clipping for Pass2-AA, revise Pass2 AA Quality parameter ..
  commit 6363ae5fb6975a6f2e7c1093ce81f25b699e3e61