* pay attention to import specs!

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

* parse module headers, augment Interface with info from header

* include file revision info in module headers

* handle scoped type variables in the parser

* For a re-exported declaration, remap its original names to names that are
  "closer" to the current module (might need to rename decls twice: once
  for docs with import_env, and once for export with orig_env).  This is
  the final support needed to fully "hide" modules from the output.

* fixities

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

* doc strings for: function arguments

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

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

* enhance the doc string parser:
	* @...@ for monospaced text
	* an apostrophe inside a string shouldn't be considered to be a quote
	* `..' instead of '..' ?

* Handle parse errors better in doc strings

* Do proper dependency analysis rather than relying on laziness to
  sort it out.