Context menu integration.
Apply button next to Save button.
Added Delete button and drag handles for items in "Nested auxiliary models" / "List of values".
[ZD-8182] Display section titles for all nested models; UI seems clearer.
Can now reorder attributes in template.
[ZD-7994] Expanded fix in 3.9 to allow describable supertypes to be intermediate in the type hierarchy (e.g. SimpleParameterDefinition).