1. added present(),presentish() and disconnect() to DXCron so that you can see

1. added present(),presentish() and disconnect() to DXCron so that you can see
(easily) if a station is on the cluster anywhere and also disconnect them
locally.
2. added rcmd() to DXCron so you can send an rcmd to someone else from crontab.
3. <embarrassment>Fixed create_sysop.pl so that longitude is spelt correctly
there as well</embarrassment> made the update work properly. NOTE create_sysop
will only do what you expect if all cluster.pl and client.pl programs are
stopped.
4. DXCron wasn't reading in reliably on startup, this is now (hopefully) fixed.
the -M semantics are rather strange!
5. The -w switch is now standard on cluster.pl
6. Added last_connect() which gives the last connect time of a user (or now
if connected).
7. Added present_on(call, node) and presentish_on(ditto) which returns true if
the call is connected to the node.