read in _totalSequenceLength from the sequence array if the DNA array is empty.  we want this to be valid even when the DNA is not stored to be consistent with last version
read in _totalSequenceLength from the sequence array if the DNA array is empty.  we want this to be valid even when the DNA is not stored to be consistent with last version

glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal,glennhickey/hal