fix(menus): Remove obsolete menu customizations
docs(features): Document all (most?) features of cbcoverseas via e2e test stubs

I don't have time to figure out how to implement these, and I'm not even confident
it's possible what with the current state of Elgg plugin testability.

Hopefully Elgg will improve over time and we can revisit writing real tests.
Or we can do some work in the Evan framework to provide wrappers and write tests against those.

For now, we're just content having all the features and their motivations
explicitly spelled out with testing steps that can be executed manually if need be.