Implemented first draft of _refs

It will probably get more powerful, but it's useful immediately as just
Property-specific.  (And decently efficient.)
Added the _or() method
Added the _first method

Also fixed a bug in Wikitext.  It had been that, as soon as you added a
CompositeWikitext into the stream (eg, with _edit), everything following
it would wind up as a CompositeWikitext, screwing up QText rendering.
Fixed that, at the cost of making things even more baroque and messed-up
internally.
Added a fairly hacked version of _linkButton()

Tried to do a few things better, including adding proper string literals
to QL, but without luck.  But it's functional for now.
Release 0.3.3