ets:from_dets/2 doesn't act as documented

[Vance Shipley]

The ets:to_dets documentation is correct:
     "The DETS table is emptied before the objects are inserted."

The ets:from_dets documentation is wrong:
     "The ETS table is emptied before the objects are inserted."

The dets:from_ets documentation isn't clear:
     "Replaces the objects of the table Name with the objects 
      of the Ets table EtsTab."

The dets:to_ets documentation is correct:
     "The existing objects of the Ets table are kept unless overwritten."