Consider extending UTF8 support

[smarek]

https://github.com/Stepets/utf8.lua

if the utf8.lua would be added as git dependency (submodule), ci_targets and possibly others need to get updated, to clone recursively the lua runtime repository

[smarek]

@KOLANICH wrote
The library you reference is nothing about parsing, it is a regexp library.
The right library is likely https://github.com/starwing/luautf8

Cheers, might be, still don't know, what more UTF8/Unicode(#10) you expect of runtime. Could you maybe put up some examples / comparison with different runtime @KOLANICH ?

I've only made this ticket because of you comment #4 (comment)
And I've already included the utf8 <-> utf16 <-> unicode module as part of #5 so it even might be already solved