Be more explicit about the output of the SDF rasterizers.

* include/freetype/fttypes.h (FT_F6Dot10): Add a new data type which can be\
  used to convert the output buffer appropriately.

* include/freetype/freetype.h (FT_Render_Mode): Add information about the
  output while using `FT_RENDER_MODE_SDF'.

* include/freetype/ftimage.h (FT_Pixel_Mode): Add more information about the
  `FT_PIXEL_MODE_GRAY16' pixel mode.
3 files changed