dmd foreach loops throw exceptions on invalid UTF sequences, use replacementDchar instead

[Ola Fosheim Grøstad]

On Monday, 15 November 2021 at 19:59:40 UTC, kdevel wrote:
> You can only decode what has been (or is ment to be) encoded. 
> Except for '.', '\0', and '/' the character values (0 .. 255) 
> have no meaning within a filename.

It should probably be a system specific string-type that 
validates using the rules of the specific OS.