rev to 0.27.1
count future validations as a sign that we fell behind

Old code was basically counting how many proposers have (and validated) the LCL
removed redundant check

check is already done inside "haveConsensus".
removing this check allows to detect if current peer has fallen behind (as done in haveConsensus).

As far as positions: nodes will tend to resolve differences earlier based on network distance (and such groups now have more time to converge with each other)
document legacy consensus