forbid out of date irc servers joining the network

We have a number of servers running versions of ircd less than 1.10. They're not supporting the new dronebl lookup which, in turn, opens our network to flooding. Also, many of these older servers contain bugs that may affect the network and/or are misconfigured (there's one that doesn't have a U:line for services so I may have to jupiter that until it's fixed).

I would suggest that, with help from @rswindell with an increase in version, vert could update to the latest version and cvs could stay at the current version for a couple of weeks to allow sysops to upgrade so we don't lose the entire network.

Or, we can permit clients to operate behind one level as long as they are at 1.10 or above. There's a few options, but we really need to get everyone on 1.10.

Finally, I've tried contacting sysops directly through their BBS but it seems like some of them are slow to respond, or just don't care.