Add Gast class with all generic functions needed
Steffen suggested that the necessary
derives are automatically generated by
makecleantest. This is complicated, since you may need to derive generics for child types, however, you should not derive those types which are already derived elsewhere (e.g., in Gast). So I'm postponing that part of clean-test#11 (moved) for the moment, but this generic class will allow one to write
derive class Gast ... which should make life a little easier.