Change from pickle to hdf5

[pdh21]

Saving xid+ classes as pickles is not a good idea. Would be better to move to something like hdf5. This is going to require some serious thought. Input from @yannick1974 would probably be a good idea

[ivvv]

I've read this blog on HDF5. I have also considered how to save python classes, avoiding pickles, but nothing obvious. JSON maybe, but not sure what are the limitations.

[pdh21]

Hi @ivvv I had read exactly the same blog but it seemed to raise more questions then answers. I will definitely take a look at JSON!

[yannick1974]

You won't directly save the classes to JSON (nor HDF5) like you do with pickle (or dill). You can only serialise the data from your class to a file, an implement a way to rebuild you class (in fact, we are talking about instances) from the data.