Fix about_constants koan

* nested constants accessed with relative paths

* top level constants referenced with ::

* nested classes inherit constants from the 
  enclosing classes

* sub-classes inherit from constants from the 
  parent class

* nested trumps inherited

* unless explicitly scoped

[#54145659]
Merge pull request #12 from bayendor/54145659_about_constants_master

Fix about_constants koan

[Delivers #54145659]