0032201: Visualization, TKOpenGl - unify Phong/PBR material properties getters

0032201: Visualization, TKOpenGl - unify Phong/PBR material properties getters

Graphic3d_ShaderManager::stdComputeLighting() - implementation has been adjusted
for better consistency between PBR / non-PBR.

OpenGl_Material definition has been modified to join Front/Back pair into a single uniform variable.
Common material definition now occupies 4x2 vec4 instead of 5x2 vec4.

Getters of Common material properties within Declarations.glsl
have been renamed to match PBR material syntax (e.g. take IsFront flag as function argument).
Auxliary macros (like occTextureColor()) has been renamed (like occMaterialBaseColor())
and adjusted to return material property directly instead of taking it as argument.