dirdiff.fast_insert - make append faster avoiding use of set_value
As I said before, one of most effective ways to improve dirdiff speed is avoid casting of PyObject into GObjects.
Without casting, _update_item_state that was taking 88s to show 52k files, now takes only 23s.
But this comes with a drawback, casting works like speed bump, this is the reason I named the new function unsafe_set_value to warn that wrong value may warn user or in worst case crash app.
UPDATE: as suggested by @kaiw now using set (11sec/52k files) instead of set_value (22sec/52k files)
Edited by Hugo Sena Ribeiro