Blender Git Commit Log

UI: remove outliner vertical separators

This removes the vertical bar separators between items and subitems (for closed
rows), and the vertical lines between the columns of restriction icons.

The vertical bars and lines don't really serve any useful purpose and add some
visual fuzziness and confusion. Best to concentrate the eye on the items of
content, not the separators between them.

Differential Revision: https://developer.blender.org/D4743