MIME type XML for browse template

[j.l.h.hartmann@…]

You can change the MIME header returned by MapServer for queries by using the
parameter QUERYFORMAT (in the WEB section). This works for query templates, but
not for normal ones (mode=browse). 

There would be more possibilities for AJAX applications if Mapserver CGI 
could return these templates as XML too, with the correct MIME-type and 
without the  comment header.

This would probably  require a BROWSEFORMAT option and supressing the comment.
There's a [version] tag to get at the build parameters anyway. 

And please add both keywords to the documentation.

Jan