added uncommitted norm_engine changes

Fixed comment

NORM protocol extension

Revert "Fixed potential SEGFAULT."

This reverts commit 79b81f48.
Was causing:

Assertion failed: destroyed (socket_base.cpp:154)
/bin/bash: line 5: 31344 Aborted                 ${dir}$tst
FAIL: test_many_sockets

On TravisCI.

Fixed potential SEGFAULT in socket_base.cpp

Allow TCP addresses to be re-resolved whenever there is a reconnection a...

Add the tag name to the zmq_pollitem_t struct to allow easier forward de...

Libsodium is now required if and only if --with-libsodium is used

This patch is proposed for https://github.com/zeromq/libzmq/issues/912.  If a user specifies that they want libzmq built with libsodium, and the requirement cannot be satisfied, we should error at the user so they can either A) install libsodium to a reasonable location or B) relax their requirement for libsodium support.

Previously a warning was issued in this case, causing users who wanted libsodium support not to get it, which may be discovered at a much later time when their programs didn't work as expected.

I release this patch under the LGPL v3 or any later version.

Minor change to zmq_curve_keypair doc

Added scaffolding for zmq_msg_gets

Fix MSVC8 build

The extra semicolons were introduced in 48b50cef together with the
defintion of the ZMQ_USE_SELECT macros.

add linking to librt under cmake build - fixes missing symbol

The libzmq library itself uses clock_gettime and should link w/ -lrt on linux.
Caught this issue on on Ubuntu 12.04 LTS.

Fix zmq_socket example in documentation

Issues adressed:
 - The actual data was never read from the socket, causing all even
   numbered loop iterations to fail
 - The socket variable was called server once

Fix build with ZMQ_HAVE_WINDOWS (typedef UINT_PTR fd_t; -> unsigned type...

  V547 Expression 'file_desc >= 0' is always true. Unsigned type value is always >= 0. socket_base.cpp 845
  V547 Expression 'file_desc >= 0' is always true. Unsigned type value is always >= 0. socket_base.cpp 863
  V547 Expression 'file_desc >= 0' is always true. Unsigned type value is always >= 0. socket_base.cpp 897
  http://www.viva64.com/en/d/0137/print/

workaround missing Mstcpip.h in mingw32

fix: win32 tcp_keepalive gets set even when option is -1

Remove duplicate poller decision making

The decision about the poller mechanism to use (select, poll, ...)
was done twice: once by the build system and once by the code in
poller.hpp. As the build-system can actually detect the mechanisms
available, prefer that result to the hard coded defaults in
poller.hpp.

At the same time, remove the duplicate detection of select() vs.
poll()-variant from proxy.cpp, signaler.cpp and zmq.cpp.

This patch has not been tested on many build platforms: especially
the cmake build needs testing / patching. For the other builds,
hard code the result as these these are all Windows platforms.

Added temporary CURVE debugging support