Fastai scans

Fastai extension to work with 3d medical images.

Work in progress...

Notes:

• Data must be stored as a bcolz array to use the data loaders (http://bcolz.blosc.org/).
• To visualize display 3d volumes the method x.show3d() uses ipyvolume (http://ipyvolume.readthedocs.io/).
• Examples in notebooks folder using Brats dataset (https://www.med.upenn.edu/sbia/brats2018/data.html).