ImmutableList for Python

This provides a python version of immutablelist.

Include for requirements.txt:

https://tracinsy.ewi.tudelft.nl/pubtrac/Utilities/export/200/immutablelistpy/dist/immutablelist-1.0.0.tar.gz

Include for setup.py: immutablelist@https://tracinsy.ewi.tudelft.nl/pubtrac/Utilities/export/199/immutablelistpy/dist/immutablelist-1.0.0.tar.gz"

Currently it contains only a subset of the classes of the java version, new classes will be added on an as-needed bases.

Please refer to immutablelist for more details on functionality