Add new cmap support to BDF driver * src/bdf/bdfdrivr.c (BDF_CMapRec) [FT_CONFIG_OPTION_USE_CMAPS]: New structure. (bdf_cmap_init, bdf_cmap_done, bdf_cmap_char_index, bdf_cmap_char_next) [FT_CONFIG_OPTION_USE_CMAPS]: New functions. (BDF_Get_Char_Index) [!FT_CONFIG_OPTION_USE_CMAPS]: Use only conditionally. (BDF_Face_Init): Handle `AVERAGE_WIDTH' and `POINT_SIZE' keywords. Implement new cmap handling. (bdf_driver_class): Updated.