Many applications assume the actual contents of the public types and use
that do for example forward declarations (saving them from including our
public header) which then breaks when we switch from void * to a struct
*.

I'm not convinced we were wrong, but since this practise seems
widespread enough I'm willing to (partly) step down.

Now libcurl uses the struct itself when it is built and it allows
applications to use the struct type if CURL_STRICTER is defined at the
time of the #include.

Reported-by: Peter Frühberger
Fixes #926

Instead of typedef'ing to void, typedef to their corresponding actual
struct names to allow compilers to type-check.

Assisted-by: Reinhard Max

Adds access to the effectively used http version to both libcurl and
curl.

Closes #799

The preprocessor check that sets up the 32bit defines for non-configure
builds didn't work properly for MIPS systems as __mips__ is defined for
both 32bit and 64bit. Now __LP64__ is also checked and indicates 64bit.

Reported-by: Tomas Jakobsson
Fixes #813

Makes curl connect to the given host+port instead of the host+port found
in the URL.

Previously, when a stream was closed with other than NGHTTP2_NO_ERROR
by RST_STREAM, underlying TCP connection was dropped.  This is
undesirable since there may be other streams multiplexed and they are
very much fine.  This change introduce new error code
CURLE_HTTP2_STREAM, which indicates stream error that only affects the
relevant stream, and connection should be kept open.  The existing
CURLE_HTTP2 means connection error in general.

Ref: https://github.com/curl/curl/issues/659
Ref: https://github.com/curl/curl/pull/663

As these two options provide identical functionality, the former for
SOCK5 proxies and the latter for HTTP proxies, merged the two options
together.

As such CURLOPT_SOCKS5_GSSAPI_SERVICE is marked as deprecated as of
7.49.0.

So that we only do the extra typedefs in curl_memory.h when we really
need to and avoid double typedefs.

follow-up commit to 7218b52c

Thanks-to: Steve Holme

The define is not in our name space and is therefore not protected by
our API promises.

It was only really used by libcurl internals but was mostly erased from
there already in 8aabbf5f (March 2015). This is supposedly the final
death blow to that define from everywhere.

As a side-effect, making sure _MPRINTF_REPLACE is gone and not used, I
made the lib tests in tests/libtest/ use curl_printf.h for its redefine
magic and then subsequently the use of sprintf() got banned in the tests
as well (as it is in libcurl internals) and I then replaced them all
with snprintf().

In the unlikely event that any users is actually using this define and
gets sad by this change, it is very easily copied to the user's own
code.

Supports HTTP/2 over clear TCP

- Optimize switching to HTTP/2 by removing calls to init and setup
before switching. Switching will eventually call setup and setup calls
init.

- Supports new version to “force” the use of HTTP/2 over clean TCP

- Add common line parameter “--http2-prior-knowledge” to the Curl
  command line tool.

The two options are almost the same, except in the case of OpenSSL:

CURLINFO_TLS_SESSION OpenSSL session internals is SSL_CTX *.

CURLINFO_TLS_SSL_PTR OpenSSL session internals is SSL *.

For backwards compatibility we couldn't modify CURLINFO_TLS_SESSION to
return an SSL pointer for OpenSSL.

Also, add support for the 'internals' member to point to SSL object for
the other backends axTLS, PolarSSL, Secure Channel, Secure Transport and
wolfSSL.

Bug: https://github.com/curl/curl/issues/234


Reported-by:  <dkjjr89@users.noreply.github.com>

Bug: https://curl.haxx.se/mail/lib-2015-09/0127.html
Reported-by: Michael König

Some TFTP server implementations ignore the "TFTP Option extension"
(RFC 1782-1784, 2347-2349), or implement it in a flawed way, causing
problems with libcurl. Another switch for curl_easy_setopt
"CURLOPT_TFTP_NO_OPTIONS" is introduced which prevents libcurl from
sending TFTP option requests to a server, avoiding many problems caused
by faulty implementations.

Bug: https://github.com/curl/curl/issues/481

... and stick to 1.1 for HTTP. This is in line with what browsers do and
should have very little risk.

The name of the header guard in lwIP's <lwip/opt.h> has changed from
'__LWIP_OPT_H__' to 'LWIP_HDR_OPT_H' (bug #35874 in May 2015).

Other fixes:

- In curl_setup.h, the problem with an old PSDK doesn't apply if lwIP is
used.

- In memdebug.h, the 'socket' should be undefined first due to lwIP's
lwip_socket() macro.

- In curl_addrinfo.c lwIP's getaddrinfo() + freeaddrinfo() macros need
special handling because they were undef'ed in memdebug.h.

- In select.c we can't use preprocessor conditionals inside select if
MSVC and select is a macro, as it is with lwIP.

http://curl.haxx.se/mail/lib-2015-12/0023.html
http://curl.haxx.se/mail/lib-2015-12/0024.html

for all we know now, it might be called 7.46.1

CURLOPT_RESOLVE and CURLOPT_PROXYHEADER were missing

Also sorted the list.

... and sorted curl_is_cb_data_option alphabetically

Also sorted that list alphabetically

As an alias for OBJECTPOINT. Provided to allow us to grep for all string
options easier.

Closes #425