fixed existing bug in update_file_tree() where the model was reset, but the selectionChanged callback was not updated as it was during first intialization
fixed existing bug in update_file_tree() where the model was reset, but the selectionChanged callback was not updated as it was during first intialization

jdeltoft/uPyLoader,BetaRavener/uPyLoader,BetaRavener/uPyLoader,jdeltoft/uPyLoader