- reverted commit 941be8d2.
 - fixed zmq_device implementation for latest socket_base class
 - added back zmq_device.3 man page

This reverts commit f575f252.

Conflicts:

	doc/zmq_device.txt

This reverts commit 13f3481e.

Conflicts:

	doc/zmq_device.txt
	doc/zmq_tcp.txt

This reverts commit 96bcc9e6.

* Fixed zmq_term, zmq_socket, zmq_close, zmq_setsockopt,
* zmq_getsockopt, zmq_bind, zmq_connect, zmq_send,
* zmq_recv, zmq_poll, zmq_device, zmq_stopwatch_stop
* Updated Reference Manual for these methods

* Clarified broker model and proxy model
* Added example of proxy model

- fixed unwrapped text in new man pages
- fixed over-long lines in older pages, where possible
- removed reference to old standalong devices from index page
- added refernce to new zmq_device[3] documented from index page
- some minor spelling corrections