Add program to look for false positives when n is small
Multiply mod n using a macro and shift for division.

The old way to divide a number x by 2 was to multiply by the inverse of 2
modulo n.  This is obviously more work computing x >> 1 if x is even and
(x+n) >> 1 otherwise.
Fix loop in power_of_x_int
Make init_int compliant with CUnit