4c3ed98ca2
Bring back per-viewport localview. This is based on Blender 2.79. We have a limit of 16 different local view viewports. We are using both the numpad /, as well as the regular /. Missing features: * Hack to make sure lights are always visible. * Make rendered mode with external engines to support this as well (probably just need to support this in the RNA iterators). * Support over 16 viewports by taking existing viewports out of local view. The code can use a cleanup pass in the future to unify the test to see if an object is visible (or we can use TESTBASE in more places).