Expose remote FD via zmq_msg_get(&msg, ZMQ_SRCFD)

This patch allows client applications to retrieve the remote endpoint from a message that originated from a tcp socket
Removed dead code
Merge pull request #808 from sradomski/master

Allow clients to get remote endpoint per message for TCP connections
Simplify ypipe_t and ypipe_base_t template parameters
Merge pull request #809 from hurtonm/master

Simplify ypipe_t and ypipe_base_t template parameters
ZMQ_SRCFD docs and tests

Also moved the fd field from message content to message itself
typo in docs
Merge pull request #810 from sradomski/master

ZMQ_SRCFD docs and tests
Make it explicit that the probe function doesn't modify passed message
Merge pull request #812 from hurtonm/master

Make it explicit that the probe function doesn't modify passed message
Fix some comments regarding method overriding
Merge pull request #813 from hurtonm/master

Fix some comments regarding method overriding
Replace assert with zmq_assert
Merge pull request #814 from hurtonm/master

Replace assert with zmq_assert
cmake: fixed error 'install TARGETS given no ARCHIVE DESTINATION for static library target'
Merge pull request #815 from snikulov/cmake_install_update

cmake: fixed error 'install TARGETS given no ARCHIVE DESTINATION'
windows: changed tcp port from glrpc assigned to unassigned one
Merge pull request #816 from snikulov/fix_test_windows

windows: changed tcp port from glrpc assigned to unassigned one
Only export zmq_* symbols
Fix timestamp counter on s390/s390x

Fixes #811