utils.py contains "import fill_voids" but the fill_voids.py is not available

[nadimpallipranav]

Dear Johannes,

When I tried to segment a test image, I was unable to proceed due to the absence of the fill_voids.py or even a function that does the same. I kindly request, if possible, that we include the file in the next commit.

`ImportError Traceback (most recent call last)
in ()
13
14
---> 15 from lungmask import mask
16 import SimpleITK as sitk

~/lungmask-git/lungmask/mask.py in ()
1 import numpy as np
2 import torch
----> 3 from . import utils
4 import SimpleITK as sitk
5 from .resunet import UNet

~/lungmask-git/lungmask/utils.py in ()
9 import logging
10 from tqdm import tqdm
---> 11 import fill_voids
12
13

ImportError: No module named 'fill_voids'`

Best regards

[JoHof]

fill_voids is a dependecy