Type.meet(t1, t2) returns UniversalType instead of concrete.
Type.meet(t1, t2) returns UniversalType instead of concrete.

When checking the meet of a concrete type and a universal type,
the UniversalType instance is now returned, not the concrete one.
This allows UniversalType instances to be used inside ListType, etc.

flumebase/flumebase,flumebase/flumebase