getParameter should return false when i is not 0 for MEdgeVertex and when i is...

It seems that the returned boolean of getParameter(..) was used to make the difference between a MVertex and a specialized version of the class (MEdgeVertex or MFaceVertex).

I would like to make the difference also between the two specializations. As far as I know, the modification in this merge request would not influence the existing code. However, it would be helpful for me. There are another solutions, so let me know if this one is not ok.