Uncommented VertexProgram.getMessageCombiner(). TraversalVertexProgram now makes use of TraverserSet messages to allow for combining when messages to a vertex are not necessarily to the vertex, but also to its edges,properties,etc. Uncommented TinkerGraphComputer's message combiner usage. Added GiraphMessageCombiner to wrap a TP3 message combiner appropriately. MessageType.Local only supports M->M. No more M1->M2 as edge modulation should not change the message class, only modulate it.