warning: declaration of 'struct GlobalConfig' will not be visible
outside of this function

Original commit message was:
 Don't omit CN verification in SChannel when an IP address is used.

Side-effect of this change:
 SChannel and CryptoAPI do not support the iPAddress subjectAltName
 according to RFC 2818. If present, SChannel will first compare the
 IP address to the dNSName subjectAltNames and then fallback to the
 most specific Common Name in the Subject field of the certificate.

 This means that after this change curl will not connect to SSL/TLS
 hosts as long as the IP address is not specified in the SAN or CN
 of the server certificate or the verifyhost option is disabled.

Compilation was not possible if manuel is disabled due this error:
 error: macro "hugehelp" passed 1 arguments, but takes just 0
  void hugehelp(void) {}

To allow for the addition of a global config structure and prevent
confusion between the two.

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