Steven G. Johnson

It seems like a better fix would make `wait(Timer(sec))` safe, somehow. `Timer` is an exported API, so ideally calling `wait` on a newly created `Timer` should not be a dangerous...

utf8proc implements case-folding, but I don't think it has the info for UTR21? Might require a patch to utf8proc?

See also JuliaLang/utf8proc#54

See also: ```jl julia> Unicode.normalize("Spaß", casefold=true) "spass" ```

Presumably we would only want to use this when `dest === src`? Wouldn't the existing code be faster for the out-of-place `dest !== src` case?

@timholy, I think the main concern is probably the repeated memory allocation and gc pressure in situations where one is doing circshift over and over in a loop... but I...