message: reduce sentinel values
  1000 was too large for the defined type (unsigned char). Somehow I
  didn't get a warning locally about this this
diff: @@ -112,7 +112,7 @@ typedef enum
  OSP_TEXTURE_RA8,
  OSP_TEXTURE_LA8,
  // Denotes an unknown texture format, so we can properly initialize parameters
  - OSP_TEXTURE_FORMAT_INVALID = 256,
  + OSP_TEXTURE_FORMAT_INVALID = 255,
  } OSPTextureFormat;
  // Flags that can be set on `texture2d` type OSPTexture; can be OR'ed together
  @@ -198,34 +198,43 @@ typedef enum
  OSP_HEXAHEDRON = 12,
  OSP_WEDGE = 13,
  OSP_PYRAMID = 14,
  - OSP_UNKNOWN_CELL_TYPE = 1000
  + OSP_UNKNOWN_CELL_TYPE = 255
  } OSPUnstructuredCellType;
  // OSPRay PerspectiveCamera stereo image modes
  typedef enum
  +# if __cplusplus >= 201103L
  +: uint8_t
  +#endif
  {
  OSP_STEREO_NONE,
  OSP_STEREO_LEFT,
  OSP_STEREO_RIGHT,
  OSP_STEREO_SIDE_BY_SIDE,
  - OSP_STEREO_UNKNOWN = 1000
  + OSP_STEREO_UNKNOWN = 255
  } OSPStereoMode;
  // OSPRay Curves geometry types
  typedef enum
  +# if __cplusplus >= 201103L
  +: uint8_t
  +#endif
  {
  OSP_ROUND,
  OSP_FLAT,
  OSP_RIBBON,
  - OSP_UNKNOWN_CURVE_TYPE = 1000
  + OSP_UNKNOWN_CURVE_TYPE = 255
  } OSPCurveType;
  // OSPRay Curves geometry bases
  typedef enum
  +# if __cplusplus >= 201103L
  +: uint8_t
  +#endif
  {
  OSP_LINEAR,
  OSP_BEZIER,
  OSP_BSPLINE,
  OSP_HERMITE,
  - OSP_UNKNOWN_CURVE_BASIS = 1000
  + OSP_UNKNOWN_CURVE_BASIS = 255
  } OSPCurveBasis;
  