#4 Integer theries must not use rational cannonization

[Jim Grundy]

Problems for the integer solver are canonized using rational division.
In particular "x/k = y" should not be reduced to "x = k*y", but to "(x = k*y + r) AND (0 <= r) AND (r < k)" for some fresh r.
It should be possible to find a solution for "x != 2*(x/2)" in the integer theory, which it doesn't find now.