added buffering to mkMap

Change-Id: Id790ca97c15110bc7aa14f042109dc22a020efcd
removed buffering from mkReducePipe -- provide it in combinepipe if needed

Change-Id: I5ed006b3dc13691bde174a7eb8ab5e1d4f25c988
use mkReducePipe to compute mismatchCount

Change-Id: I65485530007c723f990ba6fa03d00ffaf8ce2c7b