This stops the virtual method call from within the Renderer constructor.
The initialization here for GL had to be moved to VideoBackend, as the
Renderer constructor will not have been executed before the value is
required.
Sorts out references that cause some modules to be kept around after
backend shutdown.
Should also solve the issue with errors being thrown due to the config
being loaded after device creation, leading to the incorrect device being
used in a multi-adapter system.
Stenzek