TODO

- Rename get_table to reference_table

- Avoid allocating blob objects internally for for_data() faces

- head table access cleanup (div by zero now!)
- cache various expensive scale computation

- SFNT api?  get_num_faces?

- GNOME Bug 612402 - (hb-arm) HarfBuzz compilation fix for arm

- Make sure LangSys default feature is only applied once...

- kern/GPOS interaction

- Use size_t in sanitize?
- Better define HB_INTERNAL
- Future-proof metrics struct

hb-ot:
- Rename hb_internal_glyph_info_t to hb_ot_glyph_info_t
- Add query API for aalt-like features
- HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH vs LookupType::... mess