4 - Implement 'rand' feature.
10 - API to accept a list of languages?
12 - Remove hb_ot_shape_glyphs_closure()?
18 - Language to/from script.
24 - Add sanitize API (and a cached version, that saves result on blob user-data)
26 - BCP 47 language handling / API (language_matches?)
28 - Add hb_font_create_unscaled()?
30 - Add query / enumeration API for aalt-like features?
32 - SFNT api? get_num_faces?
34 - Add segmentation API
36 - Add hb-fribidi glue?
39 hb-view / hb-shape enhancements:
40 ===============================
42 - Add --width, --height, --auto-size, --ink-box, --align, etc?