cache within the multi handle.

truly use SSL

checks on the to-be-returned socket to make sure it truly seems to be alive
and well. For SSL connection it (only) uses OpenSSL functions.

an app can use to let libcurl only connect to a remote host and then extract
the socket from libcurl. libcurl will then not attempt to do any transfer at
all after the connect is done.

simple interface to extracting and setting cookies in libcurl's internal
"cookie jar". See the new cookie_interface.c example code.

internally, with code provided by sslgen.c. All SSL-layer-specific code is
then written in ssluse.c (for OpenSSL) and gtls.c (for GnuTLS).

As far as possible, internals should not need to know what SSL layer that is
in use. Building with GnuTLS currently makes two test cases fail.

TODO.gnutls contains a few known outstanding issues for the GnuTLS support.

GnuTLS support is enabled with configure --with-gnutls

ssluse.*: Added SSL_strerror(). Curl_SSL_engines_list() now returns a slist
which must be freed by caller.

UrlState sub-struct. Also made the engine_list exist for non-ssl builds to
make curl build.

Handle new info list CURLINFO_SSL_ENGINES.

  app to retrieve the errno variable after a (connect) failure. It will make
  sense to provide this for more failures in a more generic way, but let's
  start like this.

memory.h is included everywhere for this.

return their values

argument passing and try to convert to double only when providing data to the
external world.

warnings. Minor edits by me.

CURLINFO_HTTPAUTH_AVAIL and CURLINFO_PROXYAUTH_AVAIL

way for emacs, and vim users should provide a similar non-polluting style

for storage and retrieval of private data in the curl handle.

CURLINFO_REDIRECT_TIME and CURLINFO_REDIRECT_COUNT.