ENH: support independent specification of surface read/write format (#1600)

- adjustments to internal handling to improve run-time addition of
  other formats (eg, with additional user library)

  For example, to write a binary STL with a '.stl' extension:

    $ surfaceMeshConvert input.obj  -write-format stlb  output.stl

  Or in a sampler,
  to specify the input type without ambiguity:

  surf
  {
      type        meshedSurface;
      surface     sampling.inp;

      fileType    starcd;
      scale       0.001;
      ...
  }

STYLE: regularize naming for input/output scaling

  * -read-scale   (compat: -scaleIn)
  * -write-scale  (compat: -scaleOut)

CONFIG: change edge/surface selection name for STARCD format

- now select as "starcd" instead of "inp" to avoid naming ambiguity
  with abaqus