Prefer 'class X; class Y' instead of the short form

The person who was a strong proponent for the short form no longer works here. I believe the rest of us prefer this form.

See it rendered: https://github.com/henrik/devbook/blob/classes/styleguide/README.md#prefer-class-x-class-y-for-nested-classesmodules

- [x] HN
- [x] VA
- [x] AR
- [x] KP
- [x] TS
- [x] JK