[Q] Handle bytes in the range 0x80-0xC0 better when dealing with ISO-IR 196.

[Stephen J. Turnbull]

QUERY

Aidan Kehoe writes:

 > +		/* ASCII, or the lower control characters.
 > +                   
 > +                   Perhaps we should signal an error if the character is in
 > +                   the range 0x80-0xc0; this is illegal UTF-8. */
 > +                Dynarr_add (dst, (c & 0x7f));

Please do.  This is corrupting the data.

I don't have a clue how to recover from it, but the user should at
least be told.