- Add a large detailed comment about the use and necessity of
both the follower and leader probing optimization
- fix the log message in stepLeader that previously mixed up the
log term for the rejection and the index of the append
- improve the test via subtests
- add some verbiage in findConflictByTerm around first index
Verifiy the behavior in various v1 and v2 conf change operations.
This also includes various fixups, notably it adds protection
against transitioning in and out of new configs when this is not
permissible.
There are more threads to pull, but those are left for future commits.
