message: Make FaceGeom a reference and add comments.
diff: @@ -376,11 +376,15 @@ private:
  int side;
  public:
  - int Elem1No, Elem2No, FaceGeom;
  - ElementTransformation *Elem1, *Elem2, *Face;
  + int Elem1No, Elem2No;
  + /// @deprecated Use GetGeometryType instead
  + Geometry::Type &FaceGeom;
  + ElementTransformation *Elem1, *Elem2;
  + /// @deprecated No longer necessary
  + ElementTransformation *Face;
  IntegrationPointTransformation Loc1, Loc2;
  - FaceElementTransformations() : side(2), Face(this) {}
  + FaceElementTransformations() : side(2), FaceGeom(geom), Face(this) {}
  /** FaceElementTransformations objects are often used when
  performing the surface integrals on the interfaces between
  