[m-rev.] for review: improve unicode diagnostics

[Zoltan Somogyi]

For review by Peter.

Zoltan.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Log.uc
Type: application/octet-stream
Size: 552 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20240604/c06654b5/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: DIFF.uc
Type: application/octet-stream
Size: 17792 bytes
Desc: not available
URL: <http://lists.mercurylang.org/archives/reviews/attachments/20240604/c06654b5/attachment-0001.obj>