Added "#define occLight_Index(theId) 0" workaround allowing to compile
a single light source PBR shading program on OpenGL ES 2.0,
as it disallows non-constant index expressions (even trivially deducable at compile-time).
PBR lookup table is now automatically resized to RGBA format
when RG texture format is unsupported (OpenGL ES 2.0).
OpenGl_ShaderManager now allows compiling PBR shaders
using WebGL 1.0 + GL_EXT_shader_texture_lod extension.
PBR IBL baking GLSL program has been redisigned to use
if/else to avoid non-constant index expressions.
Diffuse baking implements packing float values into a temporary RGBA8 texture
as a fallback solution on WebGL 1.0 implementations supporting float textures
but not as FBO render targets.
OpenGl_PBREnvironment now uses GL_FRAMEBUFFER instead of GL_DRAW_FRAMEBUFFER
for compatibility with OpenGL ES 2.0.
Metallic-Roughness shading model Graphic3d_TOSM_PBR has been implemented.
New materials descriptors Graphic3d_PBRMaterial have been added to Graphic3d_MaterialAspect.
PBR shading model requires OpenGL 3.0+ or OpenGL ES 3.0+ hardware.
Environment cubemap is expected to be provided for realistic look of metallic materials.
occLight_IsHeadlight() now returns bool instead of int.
Avoid using lowp for enumerations to workaround occLight_IsHeadlight()
ignorance on Adreno 308 caused by some GLSL optimizator bugs.
OpenGl_Texture::EstimatedDataSize() - fixed estimation for Cubemap textures.
OpenGl_Sampler::applySamplerParams() - fixed uninitialized GL_TEXTURE_WRAP_R in case of GL_TEXTURE_CUBE_MAP target.
