Add meshes from Adithya, but dont how to get the mesh size series (needs

redoing of test cases maybe)

tests/3d_mesh/old/annulusg.geo

+//+
+SetFactory("OpenCASCADE");
+Sphere(1) = {0, 0, 0, 0.5, -Pi/2, Pi/2, 2*Pi};
+//+
+Sphere(2) = {-0, 0, 0, 2, -Pi/2, Pi/2, 2*Pi};
+//+
+BooleanDifference{ Volume{2}; Delete; }{ Volume{1}; Delete; }
+//+
+Physical Surface("inner1", 10000) = {1};
+//+
+Physical Surface("outer", 10001) = {2};