Classlib: Patterns: Pbind-like patterns now processRest on array items

This is only for use cases such as the following. If the pattern
returns an array in another context, processRest will not be called
on the items -- no efficiency cost *except* in this relatively rare
case.

Pbind([\key1, \key2], Pseq([[0, 1], [2, Rest(3)], [4, 5]], inf))