Features
- NavMenu: introduce NavMenu Interface/Trait (38df778), closes #11
- PostType: introduce PostTypeInterface/Trait (bce122f)
- Sidebar: introduce SidebarInterface/Trait (ade5215)
- Taxonomy: introduce TaxonomyInterface/Trait (c8b9144)
- Widget: introduce WidgetInterface/Trait (f10dcbc)
- Widget: introduce ControlAwareWidgetInterface/Trait (30547cb)