Model as dict

as per https://github.com/hyperspy/hyperspy/wiki/HSPEP1%3A-Save-models-in-the-same-hdf5-file-as-the-data

Still lacks user guide entries and tests (any ideas for them are welcome, as none similar are present at the moment)



It supports functions without closure - i.e. lambda and similar. Sticking to the standard library in this case means being limited by one of the biggest drawbacks of Python - pickling for multiprocessing.