Fixes server regex: allow addresses to start with digit.

Some users have hostnames based on their IP (something like
'192-168-0-1.ip.isp.acme.com') which causes the parser to throw an
error.

Officially, the IRC protocol still follows the RFC 952 standard (which
states hostnames can't start with a digit or hyphen), but a less strict
regex here is very unlikely to cause problems (whereas leaving the
stricter regex definatly DOES cause problems).