* Fix side bearings of `U+02CC` under Quasi-Proportional.
* Improve glyph shape for `U+02ED`.
* Add characters:
  - LEFTWARDS ARROW-TAIL (`U+2919`) ... RIGHTWARDS DOUBLE ARROW-TAIL (`U+291C`).
  - MODIFIER LETTER STRESS AND HIGH TONE (`U+A720`).
  - MODIFIER LETTER STRESS AND LOW TONE (`U+A721`).
  - BLACK HEART (`U+1F5A4`).
  - LEFT HALF CIRCLE (`U+1F907`).
  - WHITE HEART (`U+1F90D`).
