ExpressionVisitor #515: allow type literals to specify parts with no type arguments provided it is consistent
ExpressionVisitor #515: support a mix of type/declaration literals
metamodel tests #515: added tests for mix of type/declaration literals
nodes/expression visitor #515: remember in the tree if we want a declaration only (type arguments are missing)
Updated metamodel ref types with latest model changes #515
Unit: add getCallableReturnType and use it for #515