start working on higher arity endpoint codes for SEQUENCE
finish up multi-arity-limit, run the pre-existing tests
towards @_ support and increasing seqs by default

if the arity of the code for the limit is 0 and the count
is Inf, I try to pass all values so far into the code.

in addition, lists that start with a single number and then
have a limit block will now be increasing, rather than
decreasing (strange to have ... * be increasing and ... * > 5
be decreasing instead)
fix thinko about direction