Essential for working on Macs

Gets rid of .DS_Store files
enforce consistency of succn/predn
fix succorder/predorder
check the law for Enums without min/max elements
Merge pull request #214 from stew/scalaz-seven

Make the \/ constructors public constructors so that -\/ and \/- can be ...
delete coroutines which are subsumed by scala-machines

See <https://github.com/runarorama/scala-machines> for the successor.
Added IsEmpty typeclass to further specialize PlusEmpty. Added instances
for all the applicable types.
Added the K combinator to IdOps
fix EitherT scaladoc
non-empty String Gen instead of Gen.filter.
Merge pull request #219 from xuwei-k/fix-EitherT-scaladoc

fix EitherT scaladoc
isEmpty prop
fix IsEmptyLaw#emptyPlusIdentity
fix SetTest
add Set tests
fix streamInstance type
add isEmpty tests
delete unnecessary parameters
Merge pull request #222 from xuwei-k/delete-unnecessary-params

delete unnecessary parameters
fix Either#show