This is another heuristic because the "[" syntax is also the tuple
constructor start marker, but this takes care of the common cases of
indexing keywords and bracketed expressions.
This fixes#29.
This is a super-invasive update since the "zcl" package in particular
is referenced all over.
There are probably still a few zcl references hanging around in comments,
etc but this takes care of most of it.
The main "zcl" package requires a bit more care because of how many
callers it has and because of its two subpackages, so we'll take care
of that one separately.
