Add compression of hdf5 timeseries.

This is done in a seperate process so that we can dump the image in the
fastest way possible and get back a responsive ui and then compress
offline.

The uncompressed image is written 1 hdf5 dataset per file for
efficiency, when compressing we convert it into a single dataset with
the third dimension as time. This is both necessary for compression, and
kind of useful because it will allow slicing along time.
Need to close the uncompressed hdf5 file before we can delete it on
windows.
Merge pull request #14 from manoharan-lab/compression

Add compression of hdf5 timeseries.