* Add Characters:
  - WHITE HEAVY CHECK MARK (`U+2705`) (#3171).
  - NEGATIVE SQUARED CROSS MARK (`U+274E`) (#3171).
  - LATIN SMALL LETTER TURNED O OPEN-O (`U+AB43`).
  - LATIN SMALL LETTER TURNED O OPEN-O WITH STROKE (`U+AB44`).
* Add `double-storey-flat-bottom` variants for Latin/Cyrillic Lower A (`a`, `а`).
* Add `bilateral-motion-serifed` variants for Cyrillic Capital/Lower Ya (`Я`, `я`).
* Refine shape of the following characters:
  - LATIN SMALL LETTER AE (`U+00E6`).
  - LATIN SMALL LIGATURE OE (`U+0153`).
  - LATIN SMALL LETTER DB DIGRAPH (`U+0238`).
  - LATIN SMALL LETTER QP DIGRAPH (`U+0239`).
  - CYRILLIC SMALL LIGATURE A IE (`U+04D5`).
  - CYRILLIC CAPITAL LETTER KOMI DJE (`U+0502`).
  - CYRILLIC SMALL LETTER KOMI DJE (`U+0503`).
  - LATIN SMALL LETTER TURNED AE (`U+1D02`).
  - LATIN SMALL LETTER TURNED OE (`U+1D14`).
  - MODIFIER LETTER SMALL TURNED AE (`U+1D46`).
  - LATIN SMALL LETTER UE (`U+1D6B`).
  - COMBINING LATIN SMALL LETTER FLATTENED OPEN A ABOVE (`U+1DD3`) ... COMBINING LATIN SMALL LETTER AO (`U+1DD5`).
  - CYRILLIC CAPITAL LETTER DOUBLE MONOCULAR O (`U+A66C`).
  - CYRILLIC SMALL LETTER DOUBLE MONOCULAR O (`U+A66D`).
  - CYRILLIC CAPITAL LETTER DOUBLE O (`U+A698`).
  - CYRILLIC SMALL LETTER DOUBLE O (`U+A699`).
  - LATIN SMALL LETTER AA (`U+A733`).
  - LATIN SMALL LETTER AO (`U+A735`).
  - LATIN SMALL LETTER AU (`U+A737`).
  - LATIN CAPITAL LETTER OO (`U+A74E`).
  - LATIN SMALL LETTER OO (`U+A74F`).
  - MODIFIER LETTER SMALL LIGATURE OE (`U+A7F9`).
  - LATIN SMALL LETTER A REVERSED-SCHWA (`U+AB31`).
  - LATIN SMALL LETTER INVERTED OE (`U+AB40`) ... LATIN SMALL LETTER TURNED OE WITH HORIZONTAL STROKE (`U+AB42`).
  - LATIN SMALL LETTER UO (`U+AB63`).
  - MODIFIER LETTER SMALL AE (`U+10783`).
