Added "in" operator that can be used when defining constraints.
Currently only works for List[Int], Range, and List[Chisel.IntEx].
Example uses:
  params.constrain(ex => ex[Int]("this") in List(1,2,3,4))
  params.constrain(ex => ex[Int]("this") in Range(1,5))
  params.constrain(ex => ex[Int]("this") in List(ExLit(1),ex[Int]("that")))
Deleted unnecessary comments and a TODO
Merge branch 'master' into addingParameterFeatures

Conflicts:
	src/main/scala/Parameters.scala
Merge pull request #284 from ucb-bar/addingParameterFeatures

Adding parameter features