entry: Use gestures to handle pointer/touch events
entry: Use gestures to handle pointer/touch events

Similarly to GtkTextView, a GtkGestureMultiPress gesture handles
button/touch presses to initiate one selection mode or other, and
a GtkGestureDrag is used to handle text selection and DnD checks.

The code from button press/release, motion, and grab_notify handlers
has been shuffled into the actions triggered by those gestures.

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