Blender Git Loki

Outliner: Add new delete operator

In the industry standard keymap, both deleting objects and collections
were mapped to the same keys causing confusion when only collections
could be deleted through the keymap.

This adds a new delete operator to delete all selected objects and
collections, accessible from both the keymap and context menu. Now any
selected objects and collections are deleted when Delete is chosen from
the keymap. This also updates the tooltip description which was
previously undocumented.

Resolves T67462