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- Fix unmarshaling 3.4+ object_ref bugs.
A big thanks to Armin Rigo of the PyPy team.
- Add Pypy 3.6+ disassembly, e.g. pypy3.6-7.1.0 and pypy3.6-7.1.1
- Add Python 3.7.5, 2.7.16, 2.7.17rc1, and 2.7.15candidate1 as a valid releases
- convert unmarshal `if` .. `elif` code to a dictionary lookup with function entries
- Handle newer Python importlib - thanks to laike9m