fix lighting bug in occulus and improve the avatar name display size and behavior

- Fixed the lighting bug that i introduced with my work from past week on the transform stack. unfortunately i have to remove my rendering optimization for stereo... need to adress that in a follow up task.

- Fixed the avatar display name billboard size on retina display. this is now the same size as on windows or on non retina display. This also scale up the billboard in occulus in the case of retina display. it's ok but we probably need to address that with a more refine scaling depending on the final viewport size and not the screen resolution.

- Changed the billboard behavior of the avatar display name to only align it's yaw to the camera near plane so it's always facing the camera. but not following the pitch or roll of the camera.
this is good in mono and ok in the occulus, might be better with a billboard that faces the camera position for the case of the occulus. to be tested next.