"Fix" #60: Example 10 "Enumerations" broken

Object enumerations are still broken due to #58, so this removes the case types from `Color` and adds a comment explaining why.

This solution sucks, but #60 has been open for over five months now, and the problem exists even longer. We can’t have an example that doesn’t compile – we need *some* solution.

Closes #60 for now.