Added message type for constant messages
Merge pull request #630 from ulikoehler/cmsg

Optimized zmq::msg_t for constant messages
Minor fixes to doc ; added zmq_msg_init_data() assert preventing deferred segfault
Fix spaces before comments
Re-add comment line from cmsg branch
Merge pull request #629 from ulikoehler/init_data_assert

Minor doc & assert fixes