In preparation for separating the global config options from the per
operation config options, reworked the list engines code to not use a
member variable in the Configurable structure.

To help assist with the detection of incorrect return codes, as per
commits ee23d13a, 33b8960d and aba98991, updated the operate
based functions to return CURLcode error codes.

During initialisation SetHTTPrequest() may fail and cURL would return
PARAM_BAD_USE, which is equivalent to CURLE_NOT_BUILT_IN in cURL error
terms.

Instead, return CURLE_FAILED_INIT as we do for other functions that may
fail during initialisation.

warning: 'struct Configurable' declared inside parameter list

The previous test certificate contained a MD5 hash which is not
supported using TLSv1.2 with Schannel on Windows 7 or newer.

See the update to this blog post on IEInternals / MSDN:
http://blogs.msdn.com/b/ieinternals/archive/2011/03/25/
misbehaving-https-servers-impair-tls-1.1-and-tls-1.2.aspx

"Update: If the server negotiates a TLS1.2 connection with a
Windows 7 or 8 schannel.dll-using client application, and it
provides a certificate chain which uses the (weak) MD5 hash
algorithm, the client will abort the connection (TCP/IP FIN)
upon receipt of the certificate."

declaration of 'index' shadows a global declaration

... or any other systems lacking a native snprintf

When asking for an SFTP directory with NOBODY set, no directory contents
should be retrieved.

Bug: http://curl.haxx.se/mail/lib-2014-02/0155.html

... and mention the --tlsv1.[0-2] options in the --tslv1 entry

Reported-by: Hubert Kario

... and edited language slightly

it is only WHILE added to a multi handle that it can't be used with the
easy interface

This patch enables HTTP POST/PUT in HTTP2.
We disabled Expect header field and  chunked transfer encoding
since HTTP2 forbids them.
In HTTP1, Curl sends small upload data with request headers, but
HTTP2 requires upload data must be in DATA frame separately.
So we added some conditionals to achieve this.

When the multi API is used we must also ignore SIGPIPE signals when
caused by things we do, like they can easily be generated by OpenSSL.

This feature specifies the availability of cryptographic
authentication, which can be disabled at compile-time

It now disables NTLM and GSS authentication methods, and produces
compilable code when SSL is enabled.

... as documented!

... since it is never returned since a long while back.

For the avoidance of doubt, show a domain which contains the no-proxy
pattern but not at the top level.

Perform more work in between sleeps. This is work around the
fact that axtls does not expose any knowledge about when work needs
to be performed. Depending on connection and how often perform is
being called this can save ~25% of time on SSL handshakes (measured
on 20ms latency connection calling perform roughly every 10ms).

... for debug function

When allowing NTLM, the re-use connection logic was too focused on
finding an existing NTLM connection to use and didn't properly allow
re-use of other ones. This made the logic not re-use perfectly re-usable
connections.

Added test case 1418 and 1419 to verify.

Regression brought in 8ae35102 (curl 7.35.0)

Reported-by: Jeff King
Bug: http://thread.gmane.org/gmane.comp.version-control.git/242213