Q: bignum vtables

[Leopold Toetsch]

There are currently 19 bignum vtable slots, which take a BIGNUM* value 
argument of some kind. These are IMHO useless. We don't have a Parrot 
basic type like BIGNUM.

A BIGNUM (BigInteger, BigNumber) will just be a PMC, AFAIK.
So I think these entries should just get deleted.
leo