Power

The power analysis notebook. Expanded notebook text is on [google docs](https://docs.google.com/document/d/1CQPlAue1mVFOd811cKGuy4fibFs5abR-wTjaeW6Wu0I/edit?usp=sharing).
I think this can be replaced with:

```python
pos = (np.arange(0, num_cols).repeat(num_rows).reshape((num_row, num_cols)) + (arange(num_rows) * num_cols)).T
```

though that might be more difficult to read