Also:
- remove the restriction on the use of unquote in define-judgment-form
- allows limited use (I modes only) of judgment-forms in terms
- allows the use of define-relation with the search/unification
based random term generation
the error raising code, except in one place where I think the
error raising code was correct to have the plural form, so I changed
it back instead of changing the Redex test suite to match
redex patterns a bunch:
- repeats are turned into wrappers in sequences,
- names are all explicit,
- non-terminals are wrapped with `nt',
- cross patterns always have the hyphens in them.
- ellipses names are normalized (so there are no "hidden"
name equalities); this also means that repeat patterns
can have both a regular name and a mismatch name
Also, added a match-a-pattern helper macro that checks to make sure
that functions that process patterns don't miss any cases
