value: fix type narrowing of integers

The internal storage was using long int, while CLIPS itself uses long
long ints. The latter have the benefit to be always 64 bit wide, even on
32 bit machines. The type narrowing could cause trouble if indeed 64 bit
numbers were desired. They would work only on x86_64, not on i686. By
using long long internally and providing the appropriate interfaces this
can be resolved.
configure: set version to 0.3.3