SimpleITK 23ec6e9c Filter descriptions (reduced)

This tree was extracted from upstream SimpleITK by the following shell script:
  ./Utilities/UpdateFilterDescriptionsFromSimpleITK.sh
Merge branch 'sitk-upstream'
Move test to separate file, remove Reload & Test buttons

Moving the python unit test to a separate file under Testing/Python.
Update authors, and add basic readme
Adding enum widget and handling of new enum json attribute
Move DIR variables to be class-level scoped

Also check if __file__ is this module before trying to update it.