Support diff by revsion too, not only by date. This is a workaround
if the ports/INDEX file was not updated regularly.

To select a revsion, replace the value for the cgi variable
'time' with rev<revsion>, e.g.:

/cgi/ports.cgi?type=new&time=rev1.200&sektion=all

print a diff for all new ports since rev 1.200