Rate limit file generation #81
Description
If id3scan operates with the same source directory, and the same output directory, it will detect the XML files already written, and only generate XML files that don't exist.
With that information, you can rate limit the operations of the program, so it only writes out a maximum number of files at a time, like 1000 or so.
I'm not 100% sure what the full benefit of this would be, but it could be useful for large libraries.