Change GtkCalendar's inner border and separator values from hard-coded ones to using style properties.
Change GtkCalendar's inner border and separator values from hard-coded
ones to using style properties.

https://bugzilla.gnome.org/show_bug.cgi?id=624779

johne53/MB3Gtk-2,Distrotech/gtk,Distrotech/gtk,Distrotech/gtk,johne53/MB3Gtk-2,johne53/MB3Gtk-2,johne53/MB3Gtk-2,Distrotech/gtk,Unity-Technologies/gtk,Unity-Technologies/gtk,Unity-Technologies/gtk,Unity-Technologies/gtk,Distrotech/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2