Implement eqv? equivalence procedure

Tests pass
Provide the binding name as part of the procedure

Some built-in procedures will need to know the name by which they were
invoked, such as caar and friends. It is also useful for error
messages to include the name from the environment, rather than a hard-
coded value.

Tests pass
Implement procedures of CxR library

Tests pass
Implement eq? procedure the same as eqv?

No requirement to make these two procedures different, so treat them
as identical; eq? maps to the same internal function as eqv?.

Tests pass