[luatex] Unicode support

[Werner LEMBERG]

> Do you use the `uniParse.tcl` script, probably
> 
>   https://opensource.apple.com/source/tcl/tcl-14/tcl/tools/uniParse.tcl.auto.html  ,
> 
> to regenerate `slnudata.c` as soon as a new Unicode version gets
> published?

Having a closer look it seems that this file only handles the BMP
(i.e., the range U+0000 to U+FFFF), which is, well, not optimal.
Wouldn't it make thus sense to switch to an actively maintained UTF-8
library like 'luautf8'?

  https://github.com/starwing/luautf8


     Werner