Lighthouse backend - OpenGL

Implement a fullscreen single window single process OpenGL backend.

The pre-requisite for this task is resolving the fact that QtOpenGL does not currently support graphics systems that implement their own window surfaces in the same way that OpenVG does. It requires a pre-existing window system such as X11 or QWS to already have the surface integration done.

There are two JIRA tasks that will be created to resolve the above:

• QGLContext back end improvements
• EGL - continue separation of surface and context