Better logger infrastructure.
Keep track during view changes of where replica logs diverge.
Acknowledgement numbers are better than sticky commit numbers.

And allow us to successfully keep gaps in the log.
But those gaps are fussy.
Respond to sack by filling in the gap.

And rename methods for clarity.
Multiple -q options reduce log frequency.
Make sure ackno in view never goes backwards.

The primary must always use ackno, never commitno.