[tex4ht] dependencies, new and incomplete

[Karl Berry]

Deimi - this all sounds great to me. Separating doc from code generation
is excellent; that's been a problem since day one. I look forward to the
day when we can just type make and the right thing
happens. Unfortunately I don't know when I'll have a chance to help
bring all this to fruition :( ... -k

P.S. Not a big deal, apparently your gmail is configured to send only
HTML. When you have a chance, could you please change it to at least do
multipart/alternative, if not just plain text? Thanks.