Updated nn_pubsub documentation to include text regarding topics.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
nn_pubsub manual page improved

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Merge branch 'master' of github.com:nanomsg/nanomsg
API for multi-flight requests added

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Members of nn_req which are related to an individual request split off.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
nn_task split from nn_req

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
nn_task_init and nn_task_term added

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Merge remote-tracking branch 'upstream/master'