@roger64: Regarding treatment of elided forms, as I am not a french speaker, it is rather difficult for me to write rules for combining words. At the moment all distinctly spelled words are treated differently. Patches are welcome to change that.
If you want multiple languages, you do something like this:
<div lang="en">Some english text<span lang="fr">some french words</span></div>
Basically when the lang attribute exists on a tag, the contents of that tag are interpreted in the specified language. You can put a lang attribute on any tag, and they can be nested.