Really undo the deprecation of separator style properties
Really undo the deprecation of separator style properties

I hit the wrong one in the previous commit. For good measure,
undo depecation for all separator-related style properties.
They are still in use.

grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita,grubersjoe/adwaita