Allow to run l2proc on several topics.

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>
Producer adaptation to "dataset" messages.

Signed-off-by: Martin Raspaud <martin.raspaud@smhi.se>
Merge branch 'feature-aapp-and-npp' of github.com:mraspaud/trollduction into feature-aapp-and-npp