This patch fixes various warnings produced during the build the most
common warning, is the truncation of "size_t" (usually unsigned long) to
(int).  This patch explicitly casts the result to "int" in these cases
to supress the warning.  Additionally, this patch includes a fix to an
internal library load function to take a "const char *" parameter
instead of a "char *" parameter.
Signed-off-by: Keith Holman <keith.holman@windriver.com>

This patch adds a simple sha1 test program to the compilation for
testing the algorithm.  The sha1 algorithm is used for the initial
WebSocket handshake.
Signed-off-by: Keith Holman <keith.holman@windriver.com>

This patch adds a simple base64 test program to the compilation for
testing the algorithm.  The base64 algorithm is used for the initial
WebSocket handshake.
Signed-off-by: Keith Holman <keith.holman@windriver.com>

closes: #166

This patch provides an initial implementation for websocket support for
paho. For the websocket specification see RFC 6455.  The purpose of this
patch is to allow connnecting to an MQTT broker listening on a websocket
port (typically 80 [HTTP] or 443 [HTTPS]) to be able to communicate with
a client using the paho library.  Using websockets to communicate increases
the packet overhead both sending and receiving as well as additional setup
and ping packets.  However, using websockets allows for communications on
standard HTTP/HTTPS ports which are generally already configured by
firewalls to allow outside communications.

To use websockets, prefix the connection URI with either: "ws://" or
"wss://" for either websockets or secure websockets, repectfully.
Signed-off-by: Keith Holman <keith.holman@windriver.com>

To help understand the various connecting states this patch introduces
defines with the various states.  This helps make the code a bit easier
to understand.
Signed-off-by: Keith Holman <keith.holman@windriver.com>

To avoid inconsitstant definition of "bool", the definition of
mutex_type is moved into its own header file. This way, Socket.h does
not need to include Thread.h.
Signed-off-by: Juergen Kosel <juergen.kosel@softing.com>

Signed-off-by: Juergen Kosel <juergen.kosel@softing.com>

* develop: (21 commits)
  Add OpenSSL version check for X509_check_host
  Try to update OpenSSL on Ubuntu$
  Add TLS config for client and server for hostname verification #420
  Add TLS hostname check and CApath #420 #418
  Add tests for wrong protocol name #294
  Check for bad protocol name #294
  Check for SSLOptions structure when SSL protocol prefix is used #334
  Update CONTRIBUTING.md CLA info
  Remove reference to exit() function #342
  Reinstate tests for appveyor
  Enclose references to OsWrapper in #if defines
  Squashed commit of the following:
  Package AppVeyor artifacts attempt 1
  Create /usr/local/include if it doesn't exist #275
  Remove 373 test from Makefile... add the test source for posterity #416
  Add doc for token in ResponseOptions #411
  Add missing string.h include to SSLSocket.c
  Try AppVeyor config again
  Update AppVeyor config for latest test broker updates
  Move ListRemove after where qe is used #339
  ...

# Conflicts:
#	src/SSLSocket.c
#	test/test_issue373.c
Signed-off-by: Juergen Kosel <juergen.kosel@softing.com>

As suggested in https://github.com/eclipse/paho.mqtt.c/issues/385#issuecomment-372299490
the socket_mutex is released during the call of select(),
to avoid a performance penalty.
Signed-off-by: Juergen Kosel <juergen.kosel@softing.com>

To reduce the performance penalty of commit 779ca42a
Ian has recommended to release the socket_mutex during the call of select.
See https://github.com/eclipse/paho.mqtt.c/issues/385#issuecomment-372299490

As a preparation for this, the locking of the socket_mutex is moved inside
the Socket_getReadySocket() function.
Signed-off-by: Juergen Kosel <juergen.kosel@softing.com>

Add missing string.h include to SSLSocket.c