Blender Git Loki

Avoid possible compatibility issues with tmp viewport flags

We can't prevent users from using this branch, so I'd say it's reasonable to be a bit careful about what we store to files. In this concrete case we were storing a bit-flag for temporary use (only during early viewport transition) in a bit-field that's saved in files. Doing so would mean we either can't reuse this bit later or we risk breaking files (admittedly, likely in a pretty minor way). Moved the bit-flag to a new bit-field which can be removed later.