Stop linking to the curl.haxx.se anchor pages, they are usually only
themselves pointers to the real page so better point there directly
instead.

The protocol is named "HTTP/2" after all. It is an alias for the
existing CURL_HTTP_VERSION_2_0 enum.

Prior to this change any-domain cookies (cookies without a domain that
are sent to any domain) were exported with domain name "unknown".

Bug: https://github.com/bagder/curl/issues/292

Bug: http://curl.haxx.se/mail/lib-2015-06/0001.html
Reported-by: Rafayel Mkrtchyan

Document that if Set-Cookie is used without a domain then the cookie is
sent for any domain and will not be modified.

Bug: http://curl.haxx.se/mail/lib-2015-05/0137.html
Reported-by: Alexander Dyagilev

The CURLOPT_COOKIE doc says it "sets the cookie header explicitly in the
outgoing request(s)." However there seems to be some user confusion
about cookie modification. Document that the cookies set by this option
are not modified by the cookie engine.

Bug: http://curl.haxx.se/mail/lib-2015-05/0115.html
Reported-by: Alexander Dyagilev

Reported-by: bsammon
Bug: https://github.com/bagder/curl/issues/282

.. also correct some variable naming in curl_easy_escape.3

Bug: https://github.com/bagder/curl/issues/281


Reported-by:  <bsammon@users.noreply.github.com>

By setting this option to 1 libcurl will wait for a connection to reveal
if it is possible to pipeline/multiplex on before it continues.

Reported-by: Liviu Chircu

Reported-by: Fred Stluka
Bug: https://github.com/bagder/curl/issues/255