inspector: Use an emission hook instead of signal handlers
inspector: Use an emission hook instead of signal handlers

This is slightly easier to manage, and there's only two emission
hooks overall, instead of two signal handlers per object.

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