pr for ellipses

[quasarbright]

include examples of with and without ellipses, and the cond-like example where the ellipses are necessary to express a binding spec that would otherwise be impossible the old way.

ask whether ellipses should be fully mandatory. should too few ellipses be ok, and only error on too many?

mention the nest change (no more nest one) and its interaction with explicit vs implicit ellipses

[quasarbright]

#37