This commit adds new functions to streamline palette access:
FT_Palette_Set: Set a user-defined palette.
FT_Palette_Get: Get palette and palette index.
FT_Palette_Get_Foreground_Color: Get foreground color.
Fixes issue #1134.
* include/freetype/internal/tttypes.h (TT_FaceRec): Change type of
`palette_index` to `FT_Int`. Negative values now represent user-defined
palettes.
* src/base/ftcolor.c (FT_Palette_Set, FT_Palette_Get,
FT_Palette_Get_Foreground_Color): New functions.
* include/freetype/ftcolor.h: Updated.
9d86c63f4a