gdk3: implement Gdk::Touch accessor
gdk3: add Gdk::EventTouch tests
Merge pull request #203 from cosmo0920/implement-gdk-touch

gdk3: Implement Gdk::EventTouch accessors

Patch by cosmo. Thanks!!!
glib2 windows: bump versions

glib: 2.38.1 (There is a patch)
gmp: 5.1.3
nettle: 2.7.1
gnutls: 3.2.5

TODO: update glib-networking
gtk3: remove Gtk::BindingSet#add_path

> This function was used internally by the GtkRC parsing mechanism to
> assign match patterns to GtkBindingSet structures.

> In GTK+ 3, these match patterns are unused.
See also:
https://developer.gnome.org/gtk3/3.4/gtk3-Bindings.html#gtk-binding-set-add-path
gtk3: suppress deprecation warning
gtk3: suppress unused warning
gtk3: remove trailing spaces