bug#14647: 24.3.50; doc of `set-face-font'

[Drew Adams <drew.adams@oracle.com>]

1. Neither the Elisp manual (node `Attribute Functions') nor the doc
string says what form the string FONT must or may take.

2. The manual says that this command sets the :font attribute.  The doc
string says instead that it sets attributes :family, :foundry, :width,
:height, :weight, and :slant.  Which is it?

3. #1 is all the more imporatnt because the doc string of `x-list-fonts'
says that it returns a list of strings that are "suitable as arguments
to `set-face-font'.  Really?  Just what kind of strings are so suitable?

I think, but am not sure, that FONT must be in XLFD form.  Whatever the
acceptable form(s), the doc needs to spell this out.


In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2013-06-13 on ODIEONE
Bzr revision: 112978 xfq.free@gmail.com-20130613224333-3yfl8navh3c1vmxy
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 CFLAGS='-O0 -g3' CPPFLAGS='-Ic:/Devel/emacs/include'
 LDFLAGS='-Lc:/Devel/emacs/lib''