* src/filetree.{cc,h} (FileTree::on_treestore_rows_reordered):
New signal handler which updates the match boundaries defined by
the [path_match_first_, path_match_last_] range.  Previously this
has been handled in on_treestore_sort_column_changed(), which is
unfortunately called before the actual sorting takes place.
(FileTree::on_treestore_sort_column_changed): Remove.
(FileTree::FileTree): Connect to signal_rows_reordered() instead
of signal_sort_column_changed().