* Keep track of top level components
Currently we have to do a set comp for icons, translations,
and integration platforms every time to split the top level
components from the platforms. Keep track of the top level
components in a seperate set so avoid having to do the setcomp
every time.
* remove impossible paths
* remove unused code
* preen
* preen
* fix
* coverage and fixes
* Update homeassistant/core.py
* Update homeassistant/core.py
* Update tests/test_core.py