bring in gapstack core from prototype
gapstack core build checkpoint
gapstack test integration
fix seek past end of full gapstack
gapstack debug checkpoint 1
gapstack debug checkpoint 2: ordering invariants do not hold.
scan gapstack on each change; still debugging
note gapstack fill redesign requirement
rework gap stack fill
gap stack fill works now; remove debug
remove features from qfDyn that now live in qfSeq