This involved adding 'copy' to more generics than I hoped, but an
experiment with making it implicit showed that that way lies madness --
unless enforced, you will not remember to mark functions that don't
copy as not requiring copyable kind.
Issue #1177
These functions both use GEP_tup_like to get at the arguments bound to the
environment, but they were starting from a different 'level' of the
environment-box structure. Frighteningly, this was leading to them having
different opinions of how the bound arguments were aligned in some cases.
