OCIO: orthographic viewport perspectives disable color transform

Switching through a non-perspective view disables the OCIO color transformation until perspective is re-selected. (There is also a related Slate-Editor issue where the visible viewport label doesn't accurately represent the active perspective.)

https://udn.unrealengine.com/s/question/0D54z00008xlfQACAY/bug-in-viewport-color-management-

1. Turn on OCIO with Acescg config / game settings off / ev100 1.0
2. Have a cinecamera in your map
3. Switch viewport to Perspective view (not in camera view)
4. Switch viewport to Top view (viewport is not color managed, but that’s fine, even though it would be better)
5. Switch viewport to your cinecamera
   1. The camera view is not color managed
   2. "Perspective" view is checked in the menu, but "Top" is still displayed on the menu