Re: 23.0.60; Defaut encoding for XML files should be undefined (instead of utf-8)

[Jason Rumney]

Miles Bader wrote:
> Perhaps the "best" thing would be to temporarily do a
> (prefer-coding-system 'utf-8) when reading xml files without an encoding
> header, instead of _forcing_ the coding system to be utf-8.
>   
I made this change in sgml-xml-auto-coding-function, and also introduced 
a new function to do the same for .xml files without an xml declaration, 
which were hardcoded to utf-8 by file-coding-system-alist.

I also disabled the write-hook in nxml-mode that was forcing utf-8 on 
write, since its most important functionality of honoring changes to the 
encoding attribute in the xml declaration is already duplicated 
elsewhere in Emacs (a write equivalent of sgml-xml-auto-coding-function?).