Unsetting LAN, later setting it will strip the defaults from the
interface section so try to avoid that by always settings defaults.

CURLOPT_RETURNTRANSFER does flip the return value of curl_exec().

Always unload LAN if previously set.  Otherwise no code changes.

Boy, this is a fun one!  :) Still some work to do, but seems really
good for headless installation or just being plain sloppy.  Needed
do adapt timeout() to return the actual input char, so that we can
do the `any key' prompt.