Use Google Python docstring style

[bgottula]

https://google.github.io/styleguide/pyguide.html?showone=Comments#Comments

[bgottula]

Google style docstrings have been applied in nexstar.py. However there are still many missing docstrings in the sources for Gemini 2. Leaving this open until all source code is documented. The goal is to have no pylint errors related to missing docstrings in the entire package.