GtkGLArea: Formatting fixes
inspector: Trivial typo fix
inspector: Drop an unused argument
inspector: Store object title on object
inspector: Show object title in the misc tab
inspector: Show object title in the properties tab

Replace the search bar with a search entry in a stack to make
this work without unseemly height changes.
inspector: Show object title in the signals tab
inspector: Show object title in the gestures tab
inspector: Show object title in the css tab
inspector: Show object title in the classes tab
inspector: Show object title in hierarchy tab
inspector: Show object title in actions tab
inspector: Show object title on selector tab
inspector: Show object title on the style property list

As with the property list, this replaces the search bar by
a stack containing a search entry.
inspector: Show object title in data tab
inspector: Show object title in size groups tab
inspector: Add menu models to the tree

Add both the appmenu and the menubar models as children of the
application, if they exist.
inspector: Show object title in menu tab