Caret over wide character should be wide about vtm

[o-sdn-o]

Highlighting the current insertion point by underlining or inverting the corresponding cell is sufficient.

I closed this issue because it doesn't make sense to highlight the presence of a wide character at the insertion point. Our character handling approach allows wide characters to be halved anywhere.

Moreover, our approach assumes the use of triple and quadruple characters along with narrow and wide ones, as well as characters more than one cell high, but that's another story.