Problem after ChartWindow was disabled and enabled
again, OpenGL content was lost.

Two things:
-After setting a new OpenGLWindow the corresponding
IRenderer must be set (x3DWindowProvider->update)
-InitOpenGL() call should not depend on DummyChart, but on
OpenGLWindow (OpenGLContext).

Change-Id: If74e1945de9973d3921ceea1ca6fef39311add7a