/** Initialises the renderer.
This method can only be called after a renderer has been
selected with Root::setRenderSystem, and it will initialise
the selected rendering system ready for use.
autoCreateWindow If true, a rendering window will
automatically be created (saving a call to
RenderSystem::createRenderWindow). The window will be
created based on the options currently set on the render
A pointer to the automatically created window, if
requested, otherwise <b>NULL</b>.
RenderWindow* initialise(bool autoCreateWindow, const String& windowTitle = "OGRE Render Window");