Test for PING sent to self by reference, not name
Drop s2s UID support (servers are required to have EUID now)
Begin to expose sendto framework, to make sendto more flexible
Add a couple sendto matchers (will be useful later)
Fix CAP adding
Add timeout checking code (closes #20)
Force a maximum select() timeout of ~2 seconds

This was done so that connection timeout checks are performed on a more
regular basis. A more "efficient" method is to have each connection
determine the time interval until it would do a timeout check and then to
use that information to produce a new timeout, but that's unnecessarily
complex, especially when this solution works just fine.

I don't know if it's actually 2 seconds or not, and I can't really be
bothered to make this maximum a more concrete limit. Given the purpose
it was implemented for, this patch works perfectly.
Add u_trie_free
Only include crypt.h on systems other than OS X (closes #30)

Reported by @FionnK