Scifireaders

Several new readers and bug fixes.

- New MDT reader
- Additional WSXM support
- EMD reader updates
- bug fixes

SciFiReaders now returns a dictionary of sidpy datasets (thanks Boris)
added readers:

mrc filereader: ThermoFisher 4D STEM data file (thanks Austin)
neutron scattering file reader (thanks Rama)
bugs removed:
-emd file reader: ThermoFisher EDS spectrum images are now read correctly

Minor changes in emd reader to enable smaller memory use

compatibility with Google colab
started to return dictionaries instead of lists