Curl_expire() is now expanded to hold a list of timeouts for each easy
handle. Only the closest in time will be the one used as the primary
timeout for the handle and will be used for the splay tree (which sorts
and lists all handles within the multi handle).

When the main timeout has triggered/expired, the next timeout in time
that is kept in the list will be moved to the main timeout position and
used as the key to splay with. This way, all timeouts that are set with
Curl_expire() internally will end up as a proper timeout. Previously any
Curl_expire() that set a _later_ timeout than what was already set was
just silently ignored and thus missed.

Setting Curl_expire() with timeout 0 (zero) will cancel all previously
added timeouts.

Corrects known bug #62.

The callbacks are called when curl_multi_socket_action() is called, not
when handles are added. This is now mentioned in the "TYPICAL USAGE"
section.

In some places where the name 'stream' has been used for naming a
function argument that is in fact settable with a setopt() option we now
call that argument 'userdata' to make it more obvious that it is in fact
possible to set by the application.

Suggested by: Jeff Pohlmeyer

The SOCKET type in Win64 is 64 bits large (and thus so is curl_socket_t
on that platform), and long is only 32 bits. It makes it impossible for
curl_easy_getinfo() to return a socket properly with the
CURLINFO_LASTSOCKET option as for all other operating systems.

This one was long overdue to be mentioned in the FAQ. Also, mention the
new ftp wildcard downloading feature.

Make the multi-interface using examples use curl_multi_timeout to
properly educate users how to do things.

These two items are now actually implemented:

11.1 Content-Disposition
11.5 ftp wildcard download

... and GnuTLS connects are non-blocking, TFTP is better
integrated as a "real" protocol and RTSP is supported.

Since commit c2888604 by Jerome Vouillon

It's not quite fair to list TFTP is a "crappy" member of the
libcurl family so I removed its mentioning.

--proto tells curl to use the listed protocols for its initial
retrieval

--proto-redir tells curl to use the listed protocols after a
redirect

Also tweaked comments in certain examples using curl_multi_fdset().

curl_multi_timeout(3) is simply the wrong function to use
if you're using the multi_socket API and this document now
states this pretty clearly to help guiding users.