Improve the data structure of class Mesh, using nEdgesPerElm_

[RPIFisherman]

Before we have the first value in elm2VtxConn_ and elm2ElmConn_ work as the size number for vertices/elements connected to each element.
Now we want to use nEdgesPerElm_ to mark down the sizes of both variables (noticing nEdges = nVertices = nElms connected for each element):

polyMPO/src/pmpo_mesh.hpp

Lines 61 to 63 in 6593e01

	//IntView nEdgesPerElm_;
	IntVtx2ElmView elm2VtxConn_;
	IntElm2ElmView elm2ElmConn_;