curlx_ functions are NOT part of the offical API, but only available as source
code functions from the lib directory in case of need.

work when using proxy by converting the IDN-name to the ACE-encoded version
before the request-URL is passed to the proxy.

and then figure it out with a suitable windows call.

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.

a proxy

instead, its only for debug verbose output anyway

make the code easier to read

warnings

usage.

 threaded name resolves.

for it. It saves one extra copy of the header.

I also added comments for several functions in formdata.c

  stuff added a few weeks ago.  Turns out that if you specify --proxy-ntlm and
  communicate with a proxy that requires basic authentication, the proxy
  properly returns a 407, but the failure detection code doesn't realize it
  should give up, so curl returns with exit code 0. Test case 162 verifies
  this.

we won't try to QUIT the control connection and risk "hanging" waiting for
a response. Test case 161 verifies this. The quit-sending function was
also made static.