Outliner visibility unification: Implement 3 levels of viewport visibility

Now collection and objects can be either:
* Disabled for all the view layers.
* Hidden for a view layer but not necessarily for all others.
* Visible for a view layer but not necessarily for all others.

Regarding icons: Whatever we decide to use for the "Hidden for all view
layers" needs to be a toggle-like icon. Because when viewing "Scenes"
instead of "View Layer" in the outliner we should be able to edit the
collection "Hidden for all the view layers" as an on/off option.

The operators are accessible via a Visibility context menu or shortcuts:
* Ctrl + Click: Isolate collection (use shift to extend).
* Alt + Click: Disable collection.
* Shift + Click: Hide/Show collection and its children (objects and collections)

Things yet to be tackled:
* Object outliner context menu can also get a Visibility sub-menu.
* Get better icons for viewport enable/disable.

Note:
* When using emulate 3 button mouse alt+click is used for 2d panning.
  In this case users have to use the operator from the menu.

See T57857 for discussion.

Patch: https://developer.blender.org/D4011
Reviewers: brecht and sergey

Thanks to the reviewers and William Reynish and Julien Kasper in
particular for the feedback.

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/editors/space_outliner/outliner_ops.c b/source/blender/editors/space_outliner/outliner_ops.c
index d01fa066500..3334206beac 100644
--- a/source/blender/editors/space_outliner/outliner_ops.c
+++ b/source/blender/editors/space_outliner/outliner_ops.c
@@ -105,6 +105,16 @@ void outliner_operatortypes(void)
 	WM_operatortype_append(OUTLINER_OT_collection_holdout_clear);
 	WM_operatortype_append(OUTLINER_OT_collection_indirect_only_set);
 	WM_operatortype_append(OUTLINER_OT_collection_indirect_only_clear);
+
+	WM_operatortype_append(OUTLINER_OT_collection_isolate);
+	WM_operatortype_append(OUTLINER_OT_collection_disable);
+	WM_operatortype_append(OUTLINER_OT_collection_enable);
+	WM_operatortype_append(OUTLINER_OT_collection_hide);
+	WM_operatortype_append(OUTLINER_OT_collection_show);
+	WM_operatortype_append(OUTLINER_OT_collection_disable_render);
+	WM_operatortype_append(OUTLINER_OT_collection_enable_render);
+	WM_operatortype_append(OUTLINER_OT_collection_hide_inside);
+	WM_operatortype_append(OUTLINER_OT_collection_show_inside);
 }
 
 void outliner_keymap(wmKeyConfig *keyconf)