Update all docstrings to be Google style; update examples and See Also

[rkingsbury]

I am slowly converting function/method docstrings from numpy to Google style, but this needs to be done more comprehensively throughout the codebase, especially in solution.py and activity_correction.py

Also, many docstrings contain example code snippets and See Also entries that may be out of date or no longer relevant. These should either be tested and updated or removed.