Now that csv.py's accumulate/delta functions make it easy to switch
between delta/cumulative results, we might as well make the default
results consistent.
The previous difference between n/bench_runtime vs bench_readed/
bench_simtime risked a lot of confusion.
Note we can't use delta results for n, as it doubles as a unique index
for each probe measurement. If we want consistency the only option is
cumulative results. At least that makes the decision easy.
Christopher Haster
7bc23c89b7