Lack of EQUALP hash tables

[Rob MacLachlan <RAM@CMU-CS-C.ARPA>]

I think an Equalp hashtable would also be useful because it would
allow you to use arrays and structures as keys.

In my code I have never had any great use for the case-insensitiveness
of equalp, since I use string-equal.  In fact, I think it would be
useful if there was a predicate which used eql for comparison and
descended into arrays and structures.  There have been a number of
times when I could have used such a function.

  Rob