ENH: blockMesh enhancements

- support non-uniform scaling, prescaling and cartesian coordinate
  transformations.

  Eg, stretch in one direction and then rotate
  ```
  prescale  (1.5 1 1);
  transform
  {
      origin   (0 0 0);
      rotation
      {
          type  axisAngle;
          axis  (0 0 1);
          angle 45;
      }
  }
  ```

- support "transformed" versions of blockMesh vertices, topology.
  With the additional of transformations etc, a simplistic application
  of a single scale parameter is no longer sufficient.

    new:  blMesh.vertices(true);
    old:  blMesh.vertices() * blMesh.scaleFactor();

    new:  blMesh.topology(true);
    old:  N/A

- add individual edge access for blockDescriptor.
  Saves copying and duplicate calculations.

- handle '(block face)' specification for curved faces,
  which is ok for external block faces, but likely somewhat
  questionable if used for internal block faces.