Depsgraph hack feature - experimental

Many depsgraph failures are because some data in the graph is being
recalculated too early (or not at all).

Since we better support animators with working renders, here's a hack to
allow manual additional updates on frame changes.

In Property Editor, Object, Panel "Relations Extra" you now have two
buttons:
- Extra Object Update
- Extra Data Update

This will do an extra update of object and/or its data ONLY on frame changes.
Update happens as last.

Tested on files collected in Wiki todo, several cases now work OK, especially
the lags on updates.

release/scripts/startup/bl_ui/properties_object.py

@@ -289,6 +289,9 @@ class OBJECT_PT_relations_extras(ObjectButtonsPanel, Panel):
         row.active = ((ob.parent is not None) and (ob.use_slow_parent))
         row.prop(ob, "slow_parent_offset", text="Offset")
 
+        layout.prop(ob, "extra_recalc_object")
+        layout.prop(ob, "extra_recalc_data")
+
 
 from bl_ui.properties_animviz import (MotionPathButtonsPanel,
                                       OnionSkinButtonsPanel)