Avoid a warning, return early on empty URL.

Change-Id: Ie4eb55fa52ee97eb98a5269658ce5183a287618b
opengl charts: Move the init from sc to chart2, to have the right parent.

Change-Id: I1e23329345e00e7d8e1f269c832e84d015824c0a
Fix OpenGL chart reinitializing

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