metamodel #226: added FunctionalDeclaration interface which has a list of parameters

we don't need more lists since at runtime the other lists disappear
cosmetic: import cleanup and added a FIXME
metamodel #226: refactored Declaration into TopLevelOrMemberDeclaration
metamodel #226: Introduced Declaration and AnnotatedDeclaration
metamodel #226: renamed Parameter -> ParameterDeclaration
metamodel #226: pulled annotations() to AnnotatedDeclaration and implement it in module/package/parameter
metamodel #226: renamed FreeDeclaration to FreeTopLevelOrMemberDeclaration