0024855: Revision of parameters of standard materials

0024855: Revision of parameters of standard materials

Improve consistency and visual appearance of predefined OCCT materials in various rendering modes, including ray-tracing:
- Increase the specular exponents (shininesses) for metallic surfaces: Brass, Bronze, Copper, Gold, Pewter, Silver, Steel, Chrome, Aluminum.
- Revise specular colors for metals: Copper, Gold, Aluminum, Silver (according to "Real-Time Rendering, 3rd Edition", AK Peters 2008).
- Increase diffuse reflection of metals: Silver, Aluminum, Chrome (to make them brighter in OpenGL mode).
- Extend Material definition by Refraction Index.
  Advanced rendering methods based on shaders or ray-tracing can utilize it to produce refraction effects.

In addition:
- Introduce three translucent materials: Water, Glass, and Diamond.
- Add Charcoal for modeling dark diffuse surfaces.

Add new TCL-based sample (materials.tcl) and test case (tests/v3d/materials/bug24855).