message: Short description of NCMesh memory optimizations in the CHANGELOG.
diff: http://mfem.org
  +Not released yet
  +================
  +- Memory optimizations in the NCMesh class, which now uses 50% less memory in
  + total. The average cost of an NC element (including the refinement hierarchy,
  + but not including the temporary face_list and edge_list) is now only about 290
  + bytes, resulting e.g. in 30-40% timing improvement in ex1.
  +
  +
  Version 3.3, released on Jan 28, 2017
  =====================================
  