Ressources rebranding for Overte
(mostly images, icon, model updated with Overte brand)
some file has been edited to replace some files (they had vircadia in the name)
Most of this has not been tested. (cause I don't build)
fixes https://github.com/vircadia/vircadia/issues/1015
also:
* new mirror and controls poster model.
* moved controls poster so it would not be obscured by the wizzard.
* updated landing point.
* ambient music volume raised a bit, we may want to have a in-worrld toggle for this later https://github.com/vircadia/vircadia/issues/1016.
* turned the zone light up a bit so it is not so dark when on low graphic settings.