Worked my through the awful Pattern-nonterminal in the completeness proof.
Painfully slow progress with a completeness proof.

I'm up to the crux of the lemma, about the way in which the
case-ambiguity is avoided.
Modify tests to adjust for recent PEG changes.

A bunch of non-terminals have been removed from the PEG (not the
grammar); and there is no longer any need for the tests to check for
validity as this is guaranteed by the soundness theorem.
A smidgeon more work on completeness
Merge remote-tracking branch 'origin/master' into tup+eq
toIntLang fixed