Add prettyprinter + update scala version

Use scala version 2.11-RC4 (doesn't solve any bug...)
Now can use more or less easily any input type (but ugly code)

- Implemented Parser for Array[T] inputs
- In expands methods changed $FastParsers.toElem($elem) to $_.toElem($elem)
- In FastParserImpl get the rule type by typechecking the body (c.typecheck(b).tpe)