[crossfire] good http library for new metaserver?

[Mark Wedel]

  I'm looking/thinking about the new metaserver information, as described at:
http://wiki.metalforge.net/doku.php/dev_todo:metaserver_improvements

  As mentioned in that page, using URL/HTTP for the metaserver would seem to be 
the most scalable.  But we need to decide on a library to use for that.

  I found neon installed on my linux system - must have been installed a 
dependency for something - that sort of suggests that it may be on a fair number 
of systems.

  There is also libwww.  I'm sure there are others.

  So this is really just a question to see what is out there.

  I'd also suggest this handling if the library is missing:

For the server, this is OK, unless the user has turned on the metaserver 
notification setting.  If that is set, then program terminates with error - 
either install the library, or turn of metaserver notification.

For client, maybe shouldn't be a fatal error?  Or maybe it is a fatal error 
unless something is passed into configure (configure --no-metaserver or 
something) - it would seem that for most people, this is pretty core 
functionality, but there could be some that don't need it (own server, inside 
company firewalls, whatever)