Stripped the parser down to its essentials.  Will now provide simple
rendering tools for the envisioned basics: IF, LOOP, CONTEXT,
TEMPLATE, VARIABLE/METHOD, and TEXT.

The idea will ultimately be a two-step: a second parser for the
language we'll be parsing(!), so that you'll be able to say:

document
	= if:story if:series if:page

And be able to say with confidence that the document being read conforms
to the language.