stroke-lifetime split

This version is identical in appearance to v2.0.0.

Now the code has been split into two places.

• This repo contains everything for the streamlit app.
• The new stroke-lifetime package contains all of the calculations.
• The app imports the new stroke-lifetime package.

stroke-lifetime:

• https://pypi.org/project/stroke-lifetime/3.0.0/
• https://github.com/stroke-optimist/stroke-lifetime