Don't download unnecessary pars

[MfHYoJEcYf50]

Often a set of files in a download are quite ok, and one only need to check the first, smallest par to determine this.

It would be cool if we could avoid downloading pars 2 through 9999999999999.

[switch]

Only the smallest par2 is downloaded. If any extra par2 files are needed the download will go back to the queue to fetch however many par2 files are needed.

[MfHYoJEcYf50]

Confirmed and closed.