* Add `react/no-unused-prop-types` rule
All detected unused prop types have been removed. I have attempted to
ensure these props are no longer passed in either.
* Update handling of props to avoid false positive lint errors
These cases were detected by `react/no-unused-prop-types` as being
unused props, even though they were used. These minor adjustments
prevent them from being flagged as errors.
* Update unit tests
Many of these tests were just checking that specific props were passed
from containers or to a child component. These were deleted, as I can't
imagine how they'd be useful.
* Disable `react/no-unused-prop-types` in `componentWillReceiveProps
The rule `react/no-unused-prop-types` doesn't seem to be detecting
props used within `UNSAFE_componentWillReceiveProps`. The two cases
have been disabled temporarily until we can replace these unsafe
lifecycle functions.
* eslint: Check for unused function arguments
* eslint: Ignore unused '_' in argument list
Also allow any number of '_' e.g., '__' or '___' which is to be used sparingly
* Remove and rename unused arguments
