PropView: Cache properties boxes for better genlist performance
fix leak: free propview and other views before context deletion
ffi: add manager_widget_property_get() API
ContentView: this checked in the beginning
Container Infra: add reference count support to Gui_Container, Container_Item
Container: removing data field 'CONTAINER'
clean up
Gui_Widget_Properties: change reference behavior
Container: reload win insted of unset/reset etc.
Container: implement proper undo/redo for Object Container
TODO up
ffi: fix segv for items
Container: rename API
Fix segv
Typo
Update according to upstream

 - eolian, file interface
Typo
Properties view filter box
Single generic function for updating the visual box of property
Resize object workaround for properties cache