Add sn.datum.loaderQueryRange helper function (ported from typed datum).
Update counter to use sn.datum classes.
Support power datum that get mapped to 'Power' source ID as general node datum; use Blues if 'Consumption' is key, otherwise Greens.
Fix typo.
Support use in queue.defer for callback.
Add sn.datum.multiLoader to load from multiple node IDs simultaneously.
First functioning version of chart using new general node datum API.