Create python module for implementing speech-dispatcher modules

**Is your feature request related to a problem? Please describe.**
It would be convenient to be able to write speech-dispatcher modules in python, to leverage the pypi/etc. flexibility and dynamism.

**Describe the solution you'd like**
We'd have a python module that basically exposes libspeechd_module in a pythonic way.

Start by reading the existing libspeechd_module interface and how speech-dispatcher modules use it. Determine the Python-facing API and the compatibility expectations for existing modules; done means a usable Python module exposing libspeechd_module functionality in a Pythonic form.

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