Todo:
-Handle username + password
-Add param for .issig url, like IssigSource? Now it requires a second entry
-Doc
-Allow download+extractarchive? I suppose the download part would need to be integrated differently since it first would need to download (all?) the archive(s) to {tmp} using CreateDownloadPage. Hooking up the download steam to the 7-Zip instream wouldn't work since it needs non-sequential access.
