Remove cmake as marked for removal. It is in much better state now.

Reported-by: Jon Seymour

And modify the text to refer to HTTP 2 as it isn't called "2.0".

Reported-By: Michael Wallner

Also known as "status_request" or OCSP stapling, defined in RFC6066
section 8.

Thanks-to: Joe Mason
- for the work-around for the OpenSSL bug.

This enables the CURLOPT_SSL_VERIFYSTATUS functionality.

This option can be used to enable/disable certificate status verification using
the "Certificate Status Request" TLS extension defined in RFC6066 section 8.

This also adds the CURLE_SSL_INVALIDCERTSTATUS error, to be used when the
certificate status verification fails, and the Curl_ssl_cert_status_request()
function, used to check whether the SSL backend supports the status_request
extension.

As this feature has been implemented for 7.40.0.

...as calloc() automatically clears the area of memory with zeros.

...with the exception of the start of block statement curly brackets.

For consistency, as we seem to have a bit of a mixed bag, changed all
instances of ipv4 and ipv6 in comments and documentations to use the
correct case.

Use Unix when generically writing about Unix based systems as UNIX is
the trademark and should only be used in a particular product's name.

Change CURLOPT_TIMEOUT doc to warn that if CURLOPT_TIMEOUT and
CURLOPT_TIMEOUT_MS are both set whichever one is set last is the one
that will be used.

Prior to this change that behavior was only noted in the
CURLOPT_TIMEOUT_MS doc.

worldtimeserver.com seems also no longer available.

For getting the date header its not necessary to access special
pages or even CGI scripts - all pages including the main index
reply with the date header, therefore shortened URLs to domain.
Removed worldtime.com; added pool.ntp.org.

Worth exploring

Some websites meanwhile refuse to reply to requests from ancient
browsers like IE6, therefore I've comment out this setting, but
also fixed the string to now fake IE8 if someone enables it.

Prior to this change the 10-at-a-time example showed CURLE_RECV_ERROR
for the sony website because it ends the connection when the request is
missing a user agent.