libxfce4ui: split plugins for glade into subpackage

libxfce4ui-glade is a plugin for glade, XFCE's developer said in their
IRC channel, those plugins is being used only by their developers.

Split them out.

Ubuntu also split it this way, Xubuntu is pretty popular and well-tested
distribution, follows their steps looks like a sensible choice.

srcpkgs/libxfce4ui-glade

@@ -0,0 +1 @@
+libxfce4ui

srcpkgs/libxfce4ui/template

@@ -1,7 +1,7 @@
 # Template file for 'libxfce4ui'
 pkgname=libxfce4ui
 version=4.14.1
-revision=3
+revision=4
 build_style=gnu-configure
 build_helper="gir"
 configure_args="--disable-static"
@@ -29,7 +29,15 @@ libxfce4ui-devel_package() {
 		vmove "usr/lib/*.so"
 		vmove usr/share/gtk-doc
 		if [ "$build_option_gir" ]; then
-                        vmove usr/share/gir-1.0
-                fi
+			vmove usr/share/gir-1.0
+		fi
+	}
+}
+
+libxfce4ui-glade_package() {
+	short_desc+=" - glade plugins"
+	pkg_install() {
+		vmove usr/lib/glade
+		vmove usr/share/glade
 	}
 }