Add Python support

#### Problem
Sometimes I want to take some information from C++ to another Python program. However, I have that information in GSS, and Python does not support GSS. In consequence, I have to manually convert GSS to XML or JSON and this is very impractical.

#### Describe
I would like a Python module that allows reading GSS from Python. It would be nice if it includes all functions that are also included in C++, but at least a reader module should be added.

The issue names no files or tests. Start by examining the existing C++ functions and how GSS is represented, then define the smallest Python reader scope; done means Python can read GSS without manual XML or JSON conversion.

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