Added Traian Nicolescu's patches for threaded resolver on
Windows. Plugged some potential handle and memory leaks.

Refs.
  http://curl.haxx.se/mail/lib-2004-10/0134.html
  http://curl.haxx.se/mail/lib-2004-10/0157.html

of typecasts all over

linked list for name resolved data, even on hosts/systems with only IPv4
stacks as this simplifies a lot of code.

a host name that resolves to multiple IP addresses.

memory.h is included everywhere for this.

all things up to work with encoded host names internally, as well as keeping
'display names' to show in debug messages. IDN resolves work for me now using
ipv6, ipv4 and ares resolving. Even cookies on IDN sites seem to do right.

usage.