AbstractScene adding virtual destructor and init pointers
Fix fragment shader deprecated use of gl_FragColor
Fix issue due to missing VAO (mandatory with OpenGL 3.0 core profile
Fix warning 'QOpenGLContext::swapBuffers() called with non-exposed window, behavior is undefined'
Print out context and window version information (useful to debug)
Adding basic Opengl error checking
Fix windows compatibility
Dropped GLU dependency.
Merge branch 'silenthell-master'