added a TODO list that contains things that are left to do

TODO

+Features of old 2d grid, that do not yet work:
+
+BoundaryProjections and FaceTransformations
+Periodic Grids
+Correct RefinementEdge
+
+
+
+Improvements to the parallel 2d grid:
+
+Disable linkage creation for super Vertex 
+Test parallel reading of mesh files
+
+
+Other:
+
+Get the EntityPointer Entity change done
+