Exit with failure if any requested operation could not have been carried out #11
Description
It would be immensely useful to be able to tell through e.g. rsid3 --TPE1 file.mp3 whether file.mp3 contains TPE1 or not. Right now, missing frames are reported on stderr, but for scripts it would be much easier if the status code signaled the missing frame.
More broadly speaking, if any operation could not be done as planned, rsid3 should report a non-0 status code. This most notably includes prints and deletes, which currently return 0, which is an unwanted side-effect from #7.