nghttp2 has yet again extended its callback struct and this is an
attempt to make curl compile with nghttp2 from current git

Other global options such as --libcurl, --trace and --verbose to
follow.

In order to ease the moving of global options such as the error stream,
updated the OperationConfig structure to point to the GlobalConfig.

In addition to adding support for URL specific options via the command
line with --next it is now possible to specify "next" in .curlrc.

Follow up to commit 1a9b58fc to replace the : command line option
with --next and -:.

Added initial support for --next/-: which will be used to replace the
rather confusing : command line operation what was used for the URL
specific options prototype.

A recent change seems to have slightly changed the call stack
produced by the gcc optimizer.

darwinssl: don't omit CN verification when an IP address is used

Change "==" to "=" to honor POSIX test construction.

...and added the HTTP suffix as these options are only used for HTTP2
based connections.

Other global options such as --libcurl, --trace and --verbose to
follow.

In preparation for parsing global options added the GlobalConfig
structure to the getparameter() function.

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.