Clear all history for all points for given conn.
Perform a synchronous learn read on the given connector. Following columns are returned:
dis: display name of point
point: point marker
kind: point kind
novantHis: address to sync trend data for point
Import the latest data from an connector to the local history database. This will import history for all points under given
conn. The import will be queued a background actor, and this method will return immeditatly.