v0.5.1

Bug fixes

• Fixed a bug that was causing incorrect spectral binning when the frequency
  contribution is pure isotropic.

Other changes

• More fitting examples.
• The to_dict_with_units() method is deprecated and is replaced with json()
• The json() function returns a python dictionary object with minimal required keywords,
  where the event keys are globally serialized at the root method object. In the case where
  the event key value is different from the global value, the respective key is serialized
  within the event object.
• The json() function will no longer serialize the transition_query objects for the
  named objects.