Structure for 3D Cartesian Grid created.

Unification of boundary conditions into one file.

Some changes to input file for reference cases. This should have been
done in another branch but I wanto to commit to save progress and I
don't want to deal with tswitching branches right now, I'm very busy
watching Futurama.

src/modules/mesh/2DCart/moduleMesh2DCartRead.f90

@@ -65,7 +65,7 @@ MODULE moduleMesh2DCartRead
       ALLOCATE(self%IPIV(1:self%numNodes,1:self%numNodes))
       self%K = 0.D0
       self%IPIV = 0
-      !Read nodes cartesian coordinates (x=x, y=y, z=null)
+      !Read node cartesian coordinates (x=x, y=y, z=null)
       DO e=1, self%numNodes
         READ(10, *) n, x, y
         ALLOCATE(meshNode2DCart:: self%nodes(n)%obj)