inspector: Kepp tree iter in type data
inspector: Kepp tree iter in type data

This way we don't have to clear/refill the model every time but can keep
the existing model and only update the values.

A nice side benefit is that running an update keeps the current selection.

chergert/gtk,jigpu/gtk,ahodesuka/gtk,chergert/gtk,ahodesuka/gtk,jadahl/gtk,jadahl/gtk,Adamovskiy/gtk,grubersjoe/adwaita,Adamovskiy/gtk,ahodesuka/gtk,alexlarsson/gtk,davidgumberg/gtk,Lyude/gtk-,davidgumberg/gtk,Lyude/gtk-,Adamovskiy/gtk,Adamovskiy/gtk,jadahl/gtk,davidgumberg/gtk,grubersjoe/adwaita,chergert/gtk,chergert/gtk,chergert/gtk,alexlarsson/gtk,Lyude/gtk-,jigpu/gtk,jigpu/gtk,davidgumberg/gtk,ahodesuka/gtk,chergert/gtk,jigpu/gtk,grubersjoe/adwaita,davidgumberg/gtk,ahodesuka/gtk,jigpu/gtk,chergert/gtk,davidgumberg/gtk,ahodesuka/gtk,alexlarsson/gtk,Adamovskiy/gtk,Lyude/gtk-,Lyude/gtk-,grubersjoe/adwaita,davidgumberg/gtk,Lyude/gtk-,jadahl/gtk,grubersjoe/adwaita,grubersjoe/adwaita,jadahl/gtk,jigpu/gtk,jadahl/gtk,alexlarsson/gtk,jigpu/gtk,chergert/gtk,Lyude/gtk-,Lyude/gtk-,davidgumberg/gtk,grubersjoe/adwaita,jadahl/gtk,jadahl/gtk,Adamovskiy/gtk,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,Adamovskiy/gtk,ahodesuka/gtk,alexlarsson/gtk,Adamovskiy/gtk,jigpu/gtk,ahodesuka/gtk,grubersjoe/adwaita