treeview: Reset multipress controller after 2nd click
treeview: Reset multipress controller after 2nd click

The pre-gestures code used to compare the current button press with the
previous one on !activate_on_single_click, and unset the previous event
data so ::row-activated would be emitted every 2 clicks.

So do the same with the multipress gesture and reset it after every 2nd
click to have ::row-activated emitted multiple times while manic clicking.

https://bugzilla.gnome.org/show_bug.cgi?id=735353

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