Issue: BIT-ARRAY-FUNCTIONS (version 6)

[Barry Margolin <barmar@Think.COM>]

I'd like to suggest an additional change, which seems to be consistent
with the attitude about use of bit vectors expressed in the proposal.
The BIT and SBIT functions should return 0 if asked to access outside
the bit array.  This would maintain the tautology

	(bit (bit-XXX v1 v2) n) == (logXXX (bit v1 n) (bit v2 n))

If slowing down these functions (they'd be the only array accessors
REQUIRED to check the dimensions) is considered unacceptable, then a new
accessor should be added.

                                                barmar