fix include guard
more doc
fix herit vs. compose: maybe every class containing an int should inherit from int?
This kind of code should ring a bell about something going wrong:
    const Box2D* bboxParent = dynamic_cast<const Box2D*>(parent->getInfo());
cleanup the mess

- all Node::Info* members are nowsimply Node::Info: avoid unnecessary
pointer handling!
- don't name setters like getters! at least prefix setters with sel_