Author: Dave Collins <da...@conformal.com>
Date: 2016-10-17 (Mon, 17 Oct 2016)
blockchain: Remove exported CalcPastTimeMedian func.
This removes the exported CalcPastTimeMedian function from the
blockchain package as it is no longer needed since the information is
now available via the BestState snapshot.
Also, update the only known caller of this, which is the chain state in
block manager, to use the snapshot instead. In reality, now that
everything the block manager chain state provides is available via the
blockchain BestState snapshot, the entire thing can be removed, however
that will be done in a separate to commit to keep the changes targeted.