Markup spec/ANTLR/draft

This is a rough draft that has reached a certain level of completeness. I'm calling this version "10" because that's what the file happens to be called at the moment. Probably best to contact me before hacking on it.

Aside: I realise this grammar doesn't even support a feature on this page: &lt;source>. I didn't know about that one.

This ANTLR3 code, and all ANTLR code published myself on mediawiki.org, are licensed under the GPL, as well as the GFDL. Full preamble is in a comment just below.