Viewproperties: prevent loosing view settings

Viewproperties: prevent loosing view settings

When they match the hardcoded internal settings, when they should be
kept as long as they don't match the currently set default
viewproperties.

Is saved in metadata the diff with the hardcoded internal defaults
still. A stable default reference allows to change defaults without
changing existing saved viewproperties.

CCBUG: 495878