Scanning all archives

I discovered that CAV will not scan a .7z file. These are archives created by the 7-zip program. This archiver is coming into more and more usage and CAV should be able to scan this, and all other archive formats.

See
https://forums.comodo.com/anti_virus_wishlist/scan_all_archives-t39696.0.html

and
https://forums.comodo.com/anti_virus_wishlist/support_mozilla_mail_archive_format-t40030.0.html