multiple steps with same step-index are collated together within a single cycle

[ardunn]

Due to the way steps are iterated in a cycle (pre- and post- #699), multiple steps can be collated together if there are distinct steps sharing the same step index (number). So if the step progression goes 1 $\rightarrow$ 2 $\rightarrow$ 1 $\rightarrow$ 5 and $1,000$ points are desired for each step, the first and third step will be collated together (if they are both detected as chg/dchg) resulting in a combined $1,000$ points rather than $1,000$ points each.

This can be fixed by adjusting the grouping in BEEPDatapath.iterate_steps_in_cycle and changing the groupby to include the step index counter (which must be present).