Release 0.4.0

Minor release with the following changes:

1. Added an implicit to CommonsDef that provides a sumBy method on collections of Numerics, that calculates the sum of a function of the contents. E.g. coll.sumBy(_.length) is equivalent to coll.map(_.length).sum but without generating any intermediate collections of views.
2. ReflectionUtil can now handle Char as a target type (including Option[Char] and Seq[Char]), where previously trying to construct a Char through an exception.