I've brought the tests up to scratch, except for compounds im the
parser, because I'm too damn tired to do that over SSH. It looks like
collections are right-recursive, whixh was unintended but still works
just fine.
I've also added the '--verbose' flag to the repl to control the
debugging output.
Several obscure bugs have been fixed, and comments have been tweaked.
Mustfail tests are still needed, but that's a low priority. See #142.
Fixed#151
