Moved the error constant switch to curl_sspi.c and added two new helper
functions to curl_sspi.[ch] which either return the constant or a fully
translated message representing the SSPI security status.
Updated socks_sspi.c and curl_schannel.c to use the new functions.

Windows 2000 Professional:  Schannel returns SEC_E_OK instead
of SEC_I_CONTEXT_EXPIRED. If the length of the output buffer
is zero and the first byte of the encrypted packet is 0x15,
the application can safely assume that the message was a
close_notify message and change the return value to
SEC_I_CONTEXT_EXPIRED.

Connection shutdown does not mean that there is no data to read
Correctly handle incomplete message and ask curl to re-read
Fixed buffer for decrypted being to small
Re-structured read condition to be more effective
Removed obsolete verbose messages
Changed memory reduction method to keep a minimum buffer of size 4096

Updated TODO information and added related MSDN articles

Fixed warning: dereferencing pointer does break strict-aliasing rules
by using a union instead of separate pointer variables.
Internal union sockaddr_u could probably be moved to generic header.
Thanks to Paul Howarth for the hint about using unions for this.

Important for winbuild: Separate declaration of sockaddr_u pointer.
The pointer variable *sock cannot be declared and initialized right
after the union declaration. Therefore it has to be a separate statement.

-i without HTTP protocol shall not include headers in the output

Since Curl_pgrsDone() itself calls Curl_pgrsUpdate() which may return an
abort instruction or similar we need to return that info back and
subsequently properly handle return codes from Curl_pgrsDone() where
used.

(Spotted by a Coverity scan)

Fixed USE_IPV6 and USE_IDN not being passed
from Makefile.vc to MakefileBuild.vc
Fixed whitespace and formatting issues
Fixed typo and format in help message

Enhanced the authentication type / mechanism detection in preparation
for the introduction of APOP support.

-J without -O shall not honor C-D filename

Previously it would use a 256 byte buffer and thus cut off very long
subject names. The limit is now upped to the receive buffer size, 16K.

Bug: http://curl.haxx.se/bug/view.cgi?id=3533045
Reported by: Anthony G. Basile

Bug: https://bugzilla.redhat.com/788526
Reported by: Enrico Scholz

forward declare the Configurable struct

Commit eeeba149 removed them and thus broke my Linux build

when calloc fails, return error! (Detected by Fortify)

Reported by: Robert B. Harris

Additionally, make hash checking ability mandatory in order to allow metalink
support in curl.

A command line option could be introduced to skip hash checking at runtime,
but the ability to check hashes should always be built-in when providing
metalink support.

Previously it could easily wrongly get repeated

The length/size options take longs so make sure to pass on such types.

Reported by: Neil Bowers
Bug: http://curl.haxx.se/mail/lib-2012-06/0001.html

Re-factored the smtp_state_*_resp() functions to 1) Match the constants
that were refactored in commit 00fddba6, 2) To be more readable and
3) To match their counterparties in pop3.c.

Verify that the "Saved to filename 'blabla'" message is only displayed when
the 'blabla' filename being used _actually_ has been specified by the server
in the Content-Disposition header.

Use relative path for unintended file creation postcheck.

Re-factored the SMTP_AUTH* constants, that are used by the state
machine, to be clearer to read.