I was surprised to see so many legacy lambda syntax examples in the
documentation. This replaces all of them with the new syntax -- excluding
the handful of cases meant to explicitly verify the legacy form is still
valid. This also adds a link to the issue in the release notes which
documents the change in syntax.
Related #664
This also replaces the slightly awkward "arguments here" reason with
"argument count" as the "what" for a typical errs.ArityMismatch
exception. It also reformats most of the constructors so that the "what"
is on the same line. This makes `grep errs.ArityMismatch **.go` more
useful as a result.
- Remove reliance on scopeOp, concentrating all the scope for creating the local
scope in (*closure).call.
- Check options at the very beginning, and include all unsupported options in the
error.
