Started fixing the sorry state of the Quick Open's Levenshtein sorting.

The sane approach is to wrap on a GtkTreeModelSort, of course.

To do: getting the selection.
Fixed Quick Open's selection-mapping, now takes the added GtkTreeModelSort into account too.

Nice!
Bumped version to 1.3.0.
Removed some incorrect iteration code that caused angry GTK+ asserts.

So great to finally have found this, was really annoying.

See: http://stackoverflow.com/questions/4646510/causing-gtk-to-abort-on-assert.