Changed wye implementation to be `pull` based
Fixed wye agains the specs
Code cleanup, removed debug lines, introduced implicit S to wye.
Consistently use nanoTime in Process.duration

The first duration emitted should always be near zero.

Considered adding further properties to check later values,
but that is slow and never perfectly sure to be accurate on all
machines and all executions.
duration test in ProcessSpec
Merge branch 'master' into duration
Merge pull request #52 from jessitron/duration

Process.duration compares millis to nanos
Merge branch 'master' of github.com:scalaz/scalaz-stream into topic/actor-wye
Merge pull request #55 from scalaz/topic/actor-wye

Implemented wye via dedicated actor.  fixes #50
Merge remote-tracking branch 'origin/master' into topic/actor-mergeN