OCIO Behavior Improvements

[Jedediah Smith]

I have been playing around with the OCIO support in MrViewer and I have some feature requests and suggestions.

1. In the OCIO config you can specify the active displays and the active views. It would be great to respect the order and number of these definitions in mrviewer. For example, if you want your default display to be "shot_grade" you could just put that first in the active_views definition in your ocio config and mrviewer would use it by default. If you want to hide the "show_log" display, you could just remove it from the list of active views, without removing the view definition itself from the ocio config.
2. When OCIO is active, it would be nice to remove the gamma options in the lut dropdown, to simplify the menu. These gamma options are not used most of the time, and it is a pain having the OCIO Views hidden in a sub-menu of the display, since these are the ones you need to access the most often.
3. If there is more than one OCIO display defined, then maybe the views of the first active display would be shown in the main dropdown, and the other active displays would be shown as sub-menus.

There also appears to be a bug:
If there is a 2nd display defined, its view transform does not appear to be applied.

I've attached a screen recording to help demonstrate the suggestion.

Thank you!

[ggarra13]

I noticed that in your second display, you did not add the view (dcip3) to the active_views list, which I am guessing you should (even if mrviewer currently does not pay attention to it).