0029283: Visualization - allow defining more than 8 light sources

0029283: Visualization - allow defining more than 8 light sources

OpenGl_ShaderManager now overrides THE_MAX_LIGHTS within built-in shading programs
so that maximum number of lights is now limited only by OpenGL hardware
(e.g. length of GLSL program, number of defined uniforms, result performance, etc.).
THE_MAX_CLIP_PLANES is now also defined by OpenGl_ShaderManager,
so that unused lights and clipping planes do not reserve extra uniforms in GLSL programs.

V3d_View::SetLightOn() does not throw exception anymore, when the number of lights exceeds 8.
Instead, OpenGl_ShaderManager::PushLightSourceState() emits warning
in case of usage of FFP providing consistent behavior with Clipping Planes number limit.

# Conflicts:
#	src/V3d/V3d_View_2.cxx