Specifically:
- make predicate symbols and variables be original (and,
in the former case, have srclocs)
- remove the originality in the quoted syntax constants
that the expansion introduces
I think there is probably something better that should be done
with those introduced syntax constants, possibly relacing
them with #f, or possibly replacing them with source location
lists, but I'm not sure how they are used, so I've just left
them in there.
(Also, very minor Rackety in check syntax)
