(struct MRealizedFont): New member id. (struct MFontDriver): New member iterate_otf_feature.
(struct MRealizedFont): New member id.
(struct MFontDriver): New member iterate_otf_feature.

xmirror/m17n-lib,xmirror/m17n-lib,xmirror/m17n-lib,xmirror/m17n-lib