Merge pull request #24 from hintjens/master

Fixed man page for CURVE key options
Merge pull request #25 from hintjens/master

Clarified use of secret/public keys
Merge pull request #26 from hintjens/master

Backporting fixes from master
Merge pull request #27 from hintjens/master

Fixed ref to zmq_socket_monitor
Merge pull request #28 from hintjens/master

Fixed configure error on non-Linux boxes
Fixed issue 578
Fixed issue 578 - corrected type usage
Doc examples with zmq_msg_close usage - parameter is 'zmq_msg_t *'

Documentation examples for zmq_msg_get and zmq_msg_more functions have an
incorrect call to zmq_msg_close function - with 'zmq_msg_t' as a parameter
despite 'zmq_msg_t *' is required, so it is impossible to compile these
examples properly.

Also for zmq_msg_get example - declaration of zmq_msg_t variable is added
(like it is done in other examples).
Updated NEWS