Dis-ambiguate these two MoveReference(...) methods.

Change-Id: I08503b1e8ec20c3a236d4ee823efae84a4be54a1
Use one map type for both column and row mapping.

Change-Id: I7581ece97113acc88ff12fabec66c46c706bad3e
Set up a new undo sort mechanism.  It's empty for now.

Change-Id: I14a235f050d64d64d1102a688a304249afacf802