Actually use intltool to merge in the AppData translations

Doing the .xml.in->.xml in configure works for paths, but not translations.
Fixed warning in recent_add() and recent_remove() when path is not absolute
by prepending g_get_current_dir() to it.
Report parsing error when loading a project.
Fixes Bug 712289 "Glade silently fails to open malformed ui file"
Sort object dependancy before saving using a topological
sorting algorithm _glade_tsort() instead of g_list_sort() with
glade_widget_depends() which is not a transitive property.

Closes Bug 709609 "[PATCH] Change way of sorting before writing XML output."
Fixes Bug 711858 "editing glade project results in long CPU usage spikes after upgrading to 3.16 and GTK+3.10"
Added toplevel-order test