gchanan

Numpy allows dimensional operations on scalars, but requires that the dimension passed in is None, 0 (or -1, which is equivalent with wrap_dim): ``` >>> np.array(5).sum(None) 5 >>> np.array(5).sum(0) 5...

This currently fails, but should pass: ``` Type & T = CPU(kFloat); auto t = T.ones({0}); // FIXME: you should be able to reduce over size {0} try { t.sum(0);...