Updated Spanish translation
Minimum current gtk+ version 3.9.0

Signed-off-by: Ignacio Casal Quinteiro <icq@gnome.org>
Use titlebar at GtkHeaderBar

Signed-off-by: Ignacio Casal Quinteiro <icq@gnome.org>
Add close button

Signed-off-by: Ignacio Casal Quinteiro <icq@gnome.org>
Use GtkButton subclasses instead of GdHeaderButton ones

Signed-off-by: Ignacio Casal Quinteiro <icq@gnome.org>
Dot not use GdHeaderBar
Fix warning