Monads are back
On `Stop orElse p`, return p.  Fixes #3.
Yield all lefts for a particular K value in Tee.hashJoin, not just the last one.
Distribute orElse right only to failure case in Await.  Fixes empty hashJoins.
Require scalacheck for tests.
Simple test that hashJoin is a proper inner join.
Merge pull request #4 from S11001001/topic/hash-join-emits

hashJoin, orElse fixes
added impure drivers
idProcedure and Driver.Id; M specialized to Id for impurities.
Curry tee.
Tie the knot in Plan.repeatedly.
foreach and iterative Plan.andThen.  Fixes some overflows.
Always fold right in traversePlan.  Right-associative flatMaps are better.
transduce now works on arbitrary LinearSeqs
cleaned up debugging statements
Trial adding a fold left style interface for driver.
Merge pull request #6 from markhibberd/master

Add left fold style interface for Driver without Monoid constraint (See #5)
Renamed drivef to driveLeft.  #5
Fixed #7
Renamed TestRepeatedly and fixed permissions on TestTee.