Implement pow(3, 2)
Implemnt Integer::is_negative() and more tests
Allow 2**(-6)
Implement (2/3)^(-6)
Implement general 4/2 and things like 1*(1/2)
Add more tests
Enable 2 + 3/5
Add another test
Implement 2/3 - 3
Implement (2/3) / 3
Enable and fix another test
Another test
Merge pull request #45 from certik/rat

Implement various arithmetic with Rationals