* more compact rendering for datatypes, like
	data T = -- comment for T
	   A	 -- comment for A
	 | B     -- comment for B

* instances: list relevant instances in the documentation for classes and
  datatypes.

* attributes for individual declarations, eg.
    -- #abstract
  or targetted to a specific decl:
    -- #T: abstract

* A module re-export should only reference the target module if the
  target module is imported without hiding any of its exports (otherwise
  we should inline just the exported bits).

* facilities for saving interfaces so that you can run Haddock against
  something that isn't the Prelude.

* Do the unlitting/CPPing from Haddock itself so we get the source file
  links right.

* Allow documentation annotations to explicitly name the entity they
  refer to.

* Add back-references from the definition to the uses of types/classes
  (perhaps in the index?)
* In the contents page, indicate portability/stability of each module
  somehow.

* remove extra whitespace from the generated HTML to save space

* split large modules into several pages (perhaps split at each
  section 1 heading?)

* pay attention to import specs!

* include file revision info in module headers

* Add a link to the defining location of a re-exported entity

* fixities

* we don't deal with records properly - exporting record selectors etc.

* remove the s/r conflicts I added to the grammar

* check handling of special types ([], (), (,) etc.)

* Horizontal lines?

* clean up the layout: don't use table cellspacing, use CSS instead

* implicit parameter support in the parser.