Remove TypeTag from Problem-specific TypeTag definitions

This is an issue once !1211 (merged) is merged. Before TypeTag was a useful suffix increasing readability and avoiding confusion with class types. With !1211 (merged) is becomes mandatory to properly qualify each TypeTag with TTag::<TypeTag>, the TTag namespace. As a consequence the TypeTag is redundant and should be removed. See 9b6dc497 for an example.