Add `--silent` option
Add `--silent` option

It sets the logging level to ERROR.

nevir/groc,gilt/groc,druide/citare-scriptum,andrewburgess/groc,JoshuaToenyes/groc,druide/citare-scriptum,erdii/groc,andrewburgess/groc,JoshuaToenyes/groc,erdii/groc,nevir/groc,gilt/groc,JoshuaToenyes/groc,JoshuaToenyes/groc,druide/citare-scriptum,andrewburgess/groc,erdii/groc,erdii/groc,andrewburgess/groc,nevir/groc,gilt/groc