Problem: Spacing-combining characters handled as composing, causing text to
take more space than expected.
Solution: Handle characters marked with "Mc" not as composing.
(closes#11282
Problem: Handling emoji characters as full width has problems with
backwards compatibility.
Solution: Only put characters in the 1f000 range in the emoji table.
Problem: Handling emoji characters as full width has problems with
backwards compatibility.
Solution: Remove ambiguous and double width characters from the emoji table.
Use a separate table for the character class.
(partly by Yasuhiro Matsumoto)
Problem: Although emoji characters are ambiguous width, best is to treat
them as full width.
Solution: Update the Unicode character tables. Add the 'emoji' options.
(Yasuhiro Matsumoto)
