0025897: Visualization, TKOpenGl - disable FBO blitting after first failure on broken...

0025897: Visualization, TKOpenGl - disable FBO blitting after first failure on broken OpenGL context

OpenGl_Context::init() - detect OpenGL 2.0+ broken context by wrong GLSL version string.
Emit error messages when OpenGL context reports version higher than actually exported.

Improve logic of methods drawing Immediate presentations and swapping the Buffers.
OpenGl_Workspace::myTransientDrawToFront - repair functionality of this flag
to always render Immediate Objects into Back Buffer.
OpenGl_Workspace::myHasFboBlit - add new flag to disable FBO blitting after first failure.