[AD] new makedoc tool

[Peter Wang <tjaden@xxxxxxxxxx>]

Hi,

If you watch the CVS commits list, you may have seen that I have written
a new makedoc tool in Haskell.  It's sitting in the makedoc CVS module.

The idea was to write a relatively clean, declarative (and therefore
easy to modify) parser which could handle most of the constructs used in
existing makedoc documents.  The parser turns makedoc documents into a
abstract syntax tree (using sweet-as algebraic datatypes).  Backends do
not have to know the details of makedoc syntax _at all_; they only work
with the AST, which is supposed to tell them everything they need to
know.  For example, style tags like <em> and even C variable & function
signatures in the '@@' lines are parsed.  Haskell won't let you forget
to update a backend when the AST changes, so it's nice for maintenance.

Currently there exist [not completely polished] backends for:

	- XML (that matches allegdoc.dtd, modulo extensions like subsections)
	- LaTeX
	- man pages
	- plain text

A DocBook backend is on the way.  The parser doesn't handle thanks._tx
or external files yet.

I hope this tool will be taken into consideration if we will be shipping
pregenerated documentation in the future.

Peter