0029528: Visualization, TKOpenGl - allow defining sRGB textures

0029528: Visualization, TKOpenGl - allow defining sRGB textures

Quantity_Color definition has been modified to store RGB components
in linear color space within Quantity_TOC_RGB type.
Standard colors defined by Quantity_NameOfColor enumeration has been updated accordingly.
New Quantity_TOC_sRGB type has been introduced to handle RGB components in non-linear sRGB color space.

OpenGl_TextureFormat class definition has been moved to dedicated files.
New method OpenGl_TextureFormat::FindFormat() replaces OpenGl_Texture::GetDataFormat().
New method OpenGl_TextureFormat::FindSizedFormat() replaces OpenGl_FrameBuffer::getColorDataFormat()
and OpenGl_FrameBuffer::getDepthDataFormat().

Graphic3d_TextureRoot::IsColorMap() - introduced new property defining
if RGB(A)8 image formats should be loaded as sRGB(A) textures or as data RGB(A) textures.
OpenGl_Texture initialization methods have been extended with new theIsColorMap argument.

vreadpixel - added argument -sRGB printing color in sRGB color space.