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)



I wanted the dictionary data to be a copy of the original map, not just a reference (so that the save dictionaries can be used as a sort of "checkpoint" )