sheets fix to avoid updating cells for empty string/None swapping
sheets fix to avoid updating cells for empty string/None swapping

also a note that there is actually some quadraticness issue present

could probably work around the issue by issuing api commands for whole
rows instead of cell by cell

tgbugs/pyontutils,tgbugs/pyontutils,tgbugs/pyontutils,tgbugs/pyontutils