Numpy Import order

The python extension will produce a segfault if it is imported after `numpy`.

``` python
import numpy as np
import wfes
mu = 1e-8

wf = wfes.solve(50, -0.1, mu, mu, 0.0)
# SEGFAULT OF DOOM
```

However, the reverse import order is okay:

``` python
import numpy as np
import wfes
# ... works
```
