added --nobackup option
added --nobackup option

jjneely/whisper,alexandreboisvert/whisper,acdha/whisper,obfuscurity/whisper,akbooer/whisper,graphite-project/whisper,graphite-server/whisper,cbowman0/whisper,deniszh/whisper,penpen/whisper,kerlandsson/whisper,piotr1212/whisper