- as a side-effect of recent changes, command-line stripping of .gz
  extensions on input was lost. For example,

      OK:    surfaceTransformPoints file.stl ...
      Fail:  surfaceTransformPoints file.stl.gz ...

- restore the previous behaviour of silently stripping the '.gz'
  extension on input.

ENH: add triSurface::New selector entry point

- for symmetry with MeshedSurface