igmpproxy: bump to 0.2.1

igmpproxy: bump to 0.2.1

The sender domain has a DMARC Reject/Quarantine policy which disallows
sending mailing list messages using the original "From" header.

To mitigate this problem, the original message has been wrapped
automatically by the mailing list software.
Point at github which is new, maintained location for igmpproxy.
Remove all patches as all have been upstreamed.

Closes FS#1456

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>