Figure out what to do with sign:breve.cyrl

[rimas-kudelis]

The brevecyrabowe glyph is currently assigned to a PUA codepoint (U+ECC0), and seems to probably have been intended for use as a combining character.

What it represents is a Cyrillic form of the (combining?) breve character, which looks a little different from its Latin counterpart.

The Unicode standard makes no distinction between Cyrillic breve (кратка) and Latin one. E.g. letter Й (U+0419 CYRILLIC CAPITAL LETTER SHORT I) is considered to be canonically equivalent to a combination of letter И (U+0418 CYRILLIC CAPITAL LETTER I) and U+0306 COMBINING BREVE. Subsequently, there is no separate codepoint assigned to кратка. However, apparently, there are cases where both Latin and Cyrillic breves are used as different marks in Cyrillic texts (see https://ru.wikipedia.org/wiki/Й and https://ru.wikipedia.org/wiki/Кратка).

I suppose it would make sense to turn brevecyrabowe into an alternative form of brevecomb and breve, and probably use this form in Cyrillic context by default, but make it possible to switch back to the default breve if there's need for that? I wonder what other fonts do in cases like this.