Add __init__.py files to some subpackages

See merge request !88

further testing. Fixed bugs in main binning routine, tested, start construction of formatter and analyzer class

Started generalization of binning routines, tested, further debugging, documentation and usage simplifications to be done

Extended skeleton for dssc class, restructured processing and routines modules for easy switch between joblib and multiprocessing

Added file handlers, prepared skeleton for updated dssc class, plot related routines to be integrated and tested.

Moved xgm and tim sub-methods in dssc module to new locations. Adapted setup.py to avoid version problem with xarray

Returns bin center instead of energy mean in xas()

Closes #9

See merge request !84