A negative number under 2s complement can never be equal to its
positive as the top bit *must* be on. If two numbers are equivalent
bit-by-bit then they are equal for both signed and unsigned numbers.
Anything other than char (which can just use print.byte to print the
hex) and byte (which prints hexes anyway), all other types may be
forced to print a hex rather than a number if PRINT_HEX is 1.
These new members are just signed versions of the previous members.
This makes type punning and usage for signed versions easier than
before (no need for memcpy).
As it has no dependencies on vm specifically, and it's more necessary
for any vendors who wish to target the virtual machine, it makes more
sense for inst to be a lib module rather than a vm module.
