Shape handling doesn't accept its own results

If for example a noise object is reused for a second simulation, the shape configuration rejects its configured shape. For example, providing an nsig = [1, 2, 3, 4, 5, 6], it's reconfigured to shape (6, 1, 1). On reuse, the shape (6, 1, 1) is considered invalid.

The pattern for shape configuration should be to compute the final shape, see if the input shape can be reconfigured to that shape or is already, and only reject when necessary.