documented the undocumented public functions in libcurl

 * Make SSL session ids get used if multiple HTTPS documents from the same

   host is requested.

To do in a future release:

To do in a future release (random order):

 * Document the undocumented libcurl functions: the printf clones (like

   curl_msprintf, curl_mfprintf, curl_msnprintf, curl_maprintf and

   curl_mvfprintf) and the string compare functions (curl_strequal

   and curl_strnequal).

 * Add configure options that disables certain protocols in libcurl to

   decrease footprint.  '--disable-[protocol]' where protocol is http, ftp,