- these shouldn't really be accessible fro external code,
  so move the structure definitions inside FlatLatticeTiling.c,
  and replace the enum with an opaque 'int'.
- this breaks some debugging code in testFlatLatticeTilingPulsar.c,
  commented out until a better fix can be found.
Original: e89a3734ca61a6790b207e397e8ab4624b31c521