bug#13268: 24.3.50; out of date doc for `next-line'

[Drew Adams]

The doc string was updated to take `line-move-visual' into account.
But only partially.  This part, I think, is not up-to-date:
 
 If you are thinking of using this in a Lisp program, consider
 using `forward-line' instead.  It is usually easier to use
 and more reliable (no dependence on goal column, etc.).
 
IIUC, `forward-line' is not going to do the job, if `line-move-visual'
is non-nil.  This part should tell Lisp users how to do the job of
moving forward a visual line.  IOW, give the equivalent, for visual
line movement, of using `forward-line' with logical lines.

In GNU Emacs 24.3.50.1 (i386-mingw-nt5.1.2600)
 of 2012-12-18 on MS-W7-DANI
Bzr revision: 111265 eliz@gnu.org-20121218190556-x9wmq083vwecgu0f
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -Ic:/emacs/libs/libXpm-3.5.10/include -Ic:/emacs/libs/libXpm-3.5.10/src
 -Ic:/emacs/libs/libpng-dev_1.4.3-1_win32/include
 -Ic:/emacs/libs/zlib-dev_1.2.5-2_win32/include
 -Ic:/emacs/libs/giflib-4.1.4-1-lib/include
 -Ic:/emacs/libs/jpeg-6b-4-lib/include
 -Ic:/emacs/libs/tiff-3.8.2-1-lib/include
 -Ic:/emacs/libs/libxml2-2.7.8-w32-bin/include/libxml2
 -Ic:/emacs/libs/gnutls-3.0.9-w32-bin/include
 -Ic:/emacs/libs/libiconv-1.9.2-1-lib/include'