[R6RS] Core/lib split

[dyb at cs.indiana.edu]

> To expand on that: I was fuzzy on whether or not we decided to duplicate 
> any list library procedures in both base and 'lists', but I was under 
> the impression that we did decide that the R5RS procedures member, memq, 
> memv, assoc, assq, and assv should be in the base (in which case it 
> makes sense that memp and assp join them).

According to my notes, we decided to put them in the list library only.

As I recall, the theory is that, if we're removing I/O anyway, the base
library is really just the foundation upon which larger libraries will be
built and should be kept rather small; that we should keep the assoc,
member, and remove families together; and therefore rather than expanding
the base by adding assp, memp, and the remove family we should put all of
the assoc, member, and remove families into the list library only.

Kent