New consensus method to find bwweightscale & maxunmeasuredbw correctly.
Our original code for parsing these parameters out of our list of
parameters pre-dated us having the
dirvote_get_intermediate_param_value() function... and it was buggy.
Specifically, it would reject any " ... K=V ..." value
where there were additional unconverted characters after the V, and
use the default value instead,
We haven't run into this yet because we've never voted for
bwweightscale to be anything besides the default 10000, or
maxunmeasuredbw to be anything besides the default 20.
This requires a new consensus method because it is a change in how
consensuses are computed.
Fixes bug 19011; bugfix on 0.2.2.10-alpha.