Fix the return type of the callback to match close() and make use of it.

Introduced the initial setup to allow closesocket callbacks by making
sure sclose() is only ever called from one place in the libcurl source
and still run all test cases fine.

Commit cbf4961b garbled the timeout handling while doing SSL
handshaking (in an attempt at fixing another bug). This puts sanity
back.

Bug: http://curl.haxx.se/mail/lib-2011-05/0167.html
Reported by: Ethan Glasser Camp

The protocol handler's flags field now can set that the protocol
requires a password, so that the set_userpass function doesn't have to
have the specific knowledge of which protocols that do.

Made several functions static

Made one function defined to nothing when RTSP is disabled to avoid
the #ifdefs in code.

Removed explicit rtsp.h includes

Add a 'readwrite' function to the protocol handler struct and use that
for the extra readwrite functionality RTSP needs.

Code cleanup to check less for protocols and more for the specific
relevant feature. Like if SSL is required.

No need to check for HTTP as this is now a HTTP-specific function

make it static, remove Curl_ prefix

Also, convert the BANPROXY flag into NONETWORK for the protocols
(file:// only atm) that don't work over networks.

Using 'socks5h' as proxy protocol will make it a
CURLPROXY_SOCKS5_HOSTNAME proxy which is SOCKS5 and asking the proxy to
resolve host names. I found no "standard" protocol name for this.

closepolicy has been deprecated and unused for years

Introduce an INIT state for the SSH state machine and set libssh2
non-blocking in that so that it is set properly before
libssh2_session_startup() is called.

Bug: http://curl.haxx.se/mail/archive-2011-05/0001.html

When checking for connections that are bound to a particular device we
must make sure we don't compare with a NULL pointer.

There are systems (like NetWare) without its own gai_strerror()
function.

Now use gai_strerror() to get proper error messages when getaddrinfo()
has failed. Detect the function in configure.

Code based on work and suggestions by Jeff Pohlmeyer and Guenter Knauf

Inspired by a patch from OB.Conseil. Added test case 708 to verify.

Improved library search by check_function_exists_concat() macro:
it does not revert the list of libraries any more.

Improved OpenSSL library search: first find zlib, then search for
openssl libraries that may depend on zlib.

For Unix: openssl libraries can now be detected in nonstandard
locations. Supply CMAKE_LIBRARY_PATH to CMake on command line.

Added installation capability (very basic one yet).

When connecting to a socks or similar proxy we do the proxy handshake at
once when we know the TCP connect is completed and we only consider the
"connection" complete after the proxy handshake. This fixes test 564
which is now no longer considered disabled.

Reported by: Dmitri Shubin
Bug: http://curl.haxx.se/mail/lib-2011-04/0127.html

Source files given with absolute paths do not have the
-D directory specifier prepended.

The make target checksrc now works in the root makefile and in both the
src and lib directories.

It is also run automatically on "all" if configure --enable-debug was
used.

Useful when a known file just doesn't comply and there's no intention to
make it do so.

"if(a)" is our style, not "if( a )"

Since it now supports multiple files this will be faster and will show
problems for more file than one at a time - more convenient.

It now scans multiple files and outputs an error+warning count summary
at the end in case at least one was detected.

-D can be used to specify in which dir the files are located

The script now scans for conditions that starts with a space for
if/while/for lines.

And make the build fail if a warning or error was detected

By the use of a the new lib/checksrc.pl script that checks that our
basic source style rules are followed.

For now provide prototypes instead of including the
non-standard normalisation.h which is only available in the
"Internationalized Domain Names Mitigation APIs" download.