Calling ToTraversable on Unit. Fixes https://github.com/milessabin/shapeless/issues/273
Added HList.{partition, partitionP} & Coproduct.{partition, partitionC}

Reimplemented Filter & FilterNot type classes in terms of Partition
  (for both HList & Coproduct)

Conflicts:
	core/src/main/scala/shapeless/ops/coproduct.scala
	core/src/main/scala/shapeless/ops/hlists.scala
	core/src/main/scala/shapeless/syntax/hlists.scala
Run 'import shapeless._' in all consoles/REPLs.
Fix a few typos.

Conflicts:
	README.md
Add initial NatOps, with toInt.
Revert artefact & heterogenous.

Conflicts:
	README.md
Use path-dependant Nat type instead of type parameter.
Add a tuple updateWith function
Removed Literal type selector (now in milessabin/master as Witness type selector)
Removed Literals type selector (now in milessabin/master as HList and Coproduct type selectors)
Removed argument-less zipWithKeys overloads (now in milessabin/master)
Factored some labelled/singleton related macros for later use by Witness and HList/Coproduct type selectors

Conflicts:
	core/src/main/scala/shapeless/labelled.scala
	core/src/main/scala/shapeless/singletons.scala
Added Witness type selector

Conflicts:
	core/src/main/scala/shapeless/singletons.scala
Allowed literal types in Record/Union type selectors, and empty records/unions

Conflicts:
	core/src/main/scala/shapeless/labelled.scala
Added HList and Coproduct type selectors

Conflicts:
	core/src/main/scala/shapeless/coproduct.scala
	core/src/main/scala/shapeless/hlists.scala
Removed unused argument of ZipWithKeys dependent functions
Added argument-less zipWithKeys overloads
Removed README section about empty Record/Union type selectors (now in milessabin/master)
Removed case class conversion methods (now in milessabin/master)
Removed previously added Is prefix of Generic classes