THANKS: added names from 7.39.0 release notes
bump: towards next release
THANKS: added two missing names and removed a duplicate

./contributors.sh found these extra ones that somehow had fallen
through the cracks and never gotten added here.

Reported-by: Frank Gevaerts
Adjust OS400-specific support to last release
sspi: Define authentication package name constants

These were previously hard coded, and whilst defined in security.h,
they may or may not be present in old header files given that these
defines were never used in the original code.

Not only that, but there appears to be some ambiguity between the ANSI
and UNICODE NTLM definition name in security.h.
Remove duplicate names.

The removed names also appear as:
Andrés García, François Charlier, Gökhan Şengün, Michał Górny, Sébastien
Willemijns, Christopher Conroy, John E. Malmberg, Luca Altea, Peter Su,
S. Moonesamy, Samuel Listopad, Yasuharu Yamada, Karl Moerder
THANKS: added missing contributor from 2012
contributors.sh: filter common alternative name spellings

docs/THANKS-filter is a new filter file for converting contributor names
we get or have recorded in alternative formats to the one we already use
in THANKS. To help us show individual contributors using a single
presentation of their names.
http_digest: Use CURLcode instead of CURLdigest

To provide consistent behaviour between the various HTTP authentication
functions use CURLcode based error codes for Curl_input_digest()
especially as the calling code doesn't use the specific error code just
that it failed.
url.c: Fixed compilation warning

conversion from 'curl_off_t' to 'size_t', possible loss of data
strdup: Removed irrelevant comment

...as Curl_memdup() duplicates an area of fix size memory, that may be
binary, and not a null terminated string.
ssh: Fixed build on platforms where R_OK is not defined

Bug: http://curl.haxx.se/mail/lib-2014-11/0035.html
Reported-by: Jan Ehrhardt
http_digest: Moved algorithm definitions to SASL module
http_digest: Moved clean-up function into SASL module
http_digest: Moved challenge decoding into SASL module
http_digest: Moved response generation into SASL module
http_digest: Fixed compilation errors from commit 6f8d8131b1

error: invalid operands to binary
warning: pointer targets in assignment differ in signedness
sasl: Fixed HTTP digest challenges with spaces between auth parameters

Broken as part of the rework, in commit 7e6d51a73c, to assist with the
addition of HTTP digest via Windows SSPI.
sasl: Fixed compilation warning from commit 25264131e2

Added forward declaration of digestdata to overcome the following
compilation warning:

warning: 'struct digestdata' declared inside parameter list

Additionally made the ntlmdata forward declaration dependent on
USE_NTLM similar to how digestdata and kerberosdata are.
http_digest: Fixed memory leaks from commit 6f8d8131b1