Mesh connectivity tests for line and quad meshes.
Allow neighbors in edge/line element. Update connectivity calculation.
[MeL] Rename setElementsConnectedToElements to setNeighborElements.
[MeL] Remove extraneous element type check.
[TMeL] Replace initializer list with explicit result.
[TMeL] Add triangle/line mesh neighbor test.
Check elements dimension in addNeighbor().
renamed element neighbor method
Improve comment in ElementToElementConnectivity test.
added comment to explain identifyFace() for line elements