node_fc keyword argument not recognized

I might be missing something, but I am getting an error when trying to set a default face color for nodes:

```pgm = daft.PGM(node_fc="w",dpi = 200)```

yields the follow error:

```
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
[](https://localhost:8080/#) in ()
----> 1 pgm = daft.PGM(node_fc="w",dpi = 200)

TypeError: __init__() got an unexpected keyword argument 'node_fc'
```

If I just run `pgm = daft.PGM(dpi = 200)`, then it works.