better definition of the mappers of an input channel when there are floating nodes. fixes #216
Revert "Relax the DList conversion constraints"

This reverts commit 15777c9100414a79ee6e28c043c905df69f5c5e1.
Update build files and examples to scalaz-7.0.0-M9
Merge branch 'master' into scalaz-7.0.0-M9
slight API improvement to BasicDoFn
Tidy up some code in small ways. Use store for fields.