RE: isearch-yank-word-at-point (was Re: Key map translations)

[Drew Adams]

> (define-key isearch-mode-map "\C-_" 'isearch-yank-symbol)
> I chose '_' (underscore) as it stands for symbols in much the same way
> as 'w' stands for word.

I think it's good to reserver `C-_' for something at least somewhat related to
undoing, even in specific keymaps.

The C-_-as-undo association is stronger for most users, I think, than is the
_-as-symbol association.

Just one opinion.