#379 grip overwrites files, where it should not

[cyberbeat]

this is always the problem when ripping cds with unknown artist/titles. when ripping some more cds, grip simply overwrites the previous files.

for exmaple "unknown artist - track 1" from first cd is overwritten by "unkown artist - track 1" from the second cd.

there should be an option to automatically append some numbers to existing filenames.

[Nobody/Anonymous]

This will happen with known artists as well when a CD that's previously been ripped is re-ripped. It would be nice to have configuration settings for:

- go ahead and write over existing files
- write new files by appending an extension, perhaps based on freeDB ID number
- write temp file, compare to existing, write if different
- consider the file processed if the filename exists
- stop and wait for human intervention, including previous options