Allow Mesh2D to be given an analysis type.

[Greg-Hamel]

The Mesh2D should be able to be given an analysis type.
This analysis type will then be passed on to the elements and nodes contained within the mesh for the Ne_ref and other shape functions derived results to follow their analysis-required shape.

Here is an example of one of the differences between the heat transfer equations and the structures-based equations.

Heat transfer:
Ne_ref = [N1, N2, N3, N4, ...]

Structures:
Ne_ref = [N1, 0, N2, 0, ...]
[ 0, N1, 0, N2, ...]