... and then go through the "normal" HTTP engine.

Check the NPN result before preparing an HTTP request and switch into
HTTP/2.0 mode if necessary. This is a work in progress, the actual code
to prepare and send the request using nghttp2 is still missing from
Curl_http2_send_request().

To better reflect its purpose

NPN is what is available in the wild today to negotiate SPDY or HTTP/2.0
connections. It is expected to be replaced by ALPN in the future. If
HTTP/2.0 is negotiated, this is indicated for the entire connection and
http.c is expected to initialize itself for HTTP/2.0 instead of
HTTP/1.1.

see:
http://technotes.googlecode.com/git/nextprotoneg.html
http://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-04

This makes it easier to trace what's happening.

the number of elements in the 'nghttp2_session_callbacks' structure is
now reduced by 2 in version 0.3.0 (I'm not sure when the change
happened, but checking for ver 0.3.0 work for me).

Something is wrong in 'userp' for the HTTP2 recv_callback().  The
session is created using bogus user-data; '&conn' and not 'conn'.

I noticed this since the socket-value in Curl_read_plain() was set to a
impossible high value.

Fixed two compiler nits

...until the function is successful when it returns them in the out
parameters.

Added conversion functions write32_le() and write64_le() to ensure the
NTLMv2 timestamp is always written in little-endian.

It is not provided by NSS public headers.

Bug: https://bugzilla.redhat.com/1058776

... that the user does not ask for

hostcache_timestamp_remove() should remove old *unused* entries from the
host cache, but it never checked whether the entry was actually in
use. This complements commit 030a2b8c.

Bug: http://curl.haxx.se/bug/view.cgi?id=1327

tftp_done() can get called with its TFTP state pointer still being NULL
on an early time-out, which caused a segfault when dereferenced.

Reported-by: Glenn Sheridan
Bug: http://curl.haxx.se/mail/lib-2014-01/0246.html

Make it possible to call
curl_easy_getinfo(curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &filesize)
and related functions on remote sftp:// files, without downloading them.

Reported-by: Yingwei Liu
Bug: http://curl.haxx.se/mail/lib-2014-01/0139.html

This prevents sending a `Content-Length: -1` header, e.g this ocurred
with the following combination:

* standard HTTP POST (no chunked encoding),
* user-defined read function set,
* `CURLOPT_POSTFIELDSIZE(_LARGE)` NOT set.

With this fix it now behaves like HTTP PUT.

Make GnuTLS old and new consistent, specify the desired protocol, cipher
and certificate type in always in both modes. Disable insecure ciphers
as reported by howsmyssl.com. Honor not only --sslv3, but also the
--tlsv1[.N] switches.

Related Bug: http://curl.haxx.se/bug/view.cgi?id=1323

conversion from 'curl_off_t' to 'size_t', possible loss of data

Where curl_off_t is a 64-bit word and size_t is 32-bit - for example
with 32-bit Windows builds.

A follow up patch to commit d2671340 as _WIN32_WINNT_WIN2K and
_WIN32_WINNT_WIN2K may not be defined on all systems.