bug#10978: `calendar-string-spread' loses with double-width characters

[Eli Zaretskii]

> From: "Drew Adams" <drew.adams@oracle.com>
> Cc: <10978@debbugs.gnu.org>
> Date: Fri, 9 Mar 2012 06:05:24 -0800
> 
> > It should use `string-width' instead of `length'.
> 
> The Elisp manual has a section on `Strings and Characters', which is one of 
> the
> sections about Lisp data types. It has details about lots of string- and
> character-related functions.
> 
> Perhaps some node in that section (maybe `Text Comparison'?) should at least
> mention function `string-width' and cross-reference the node `Width' in the
> `Display' part of the manual.

I added such cross-references to "String Basics" and also to "Sequence
Functions".