HaskellModule, as planned in #99
basic parser combinators
comments and module declarations
Data.Chunks

Because I want the parser combinators to generate the three
HaskellModule sections via Writer, and I need a Monoid instance for
that.
chunk-constructors

The whole point of this data structure was to be able to easily describe
a divider between two chunks. Now it really is easy.
parser combinators now use Data.Chunks