New draft MicroXML spec

I've moved the spec from the wiki into the W3C's version control system and
fixed it up so that it meets the W3C's CG publishing requirements:

http://dvcs.w3.org/hg/microxml/raw-file/tip/spec/microxml.html

Note that the spec is polyglot HTML/MicroXML.  It's not valid (or whatever
the right word is) HTML5, because it doesn't have a DOCTYPE declaration,
but it is conforming MicroXML (according to itself).

I think this is getting very close to the point where we could formally
publish it as a draft spec; this would ensure it is linked to from
http://www.w3.org/community/reports/.

James