Add font-lock for a list of default types

I see, thanks.  Moving this toward the end of all the regexen, at least past where they might be highlighted with the function face as in `val int` or as a variable name in a `let` solves a couple problems my patch brings.

In the case where nothing else should highlight one of these words, I'm not sure how to check to make sure _not_ to highlight it as a type. I would have to check context somehow.