(chibi char-set boundary)

Char-sets used for TR29 word boundaries.

`char-set:extend-or-spacing-mark`

`char-set:regional-indicator`

`char-set:hangul-l`

`char-set:hangul-v`

`char-set:hangul-t`

`char-set:hangul-lv`

`char-set:hangul-lvt`