c_type
This is probably the wrong fix; probably I should have fixed read_string so that it did not create null-character terminated strings, but it will do for now. Probably will revisit.
It's still broken, but it's broken because of fundamental misunderstanding which tinkering won't solve.
bignum multiply is still not working, but as bignum read and bignum divide depend on it, it's the problem to hit first.
