Graphic3d_RenderTransparentMethod has been extended by Graphic3d_RTM_DEPTH_PEELING_OIT,
which is handled by OpenGl_LayerList::renderTransparent().
OpenGl_FrameBuffer::Init() now does not silently ignore unknown color attachment format and return failure.
OpenGl_FrameBuffer::InitWrapper() - added constructor wrapping existing color textures.
v3d/transparency/oit: test case added