Use new OO#initClass method for base classes

* Rename "Inheritance" section to "Setup".
* Add a "Setup" section to existing classes not having it already
  (inheritClass/mixinClass calls auto-init the relevant classes).
  So now each class has a "Setup" section, which either calls
  initClass or one or more of inheritClass/mixinClass.

Change-Id: Ibee3d0bb3b6708e0c29fb055ea57c5209d51272a