XSL major mode for emacs.

* FEATURES
 - XSL customization group for setting some variables
 - Initial stylesheet inserted into empty XSL buffers;
 - "Template" menu for jumping to template rules, named templates, key
   declarations, and attribute-set declarations in the buffer;
 - `xsl-process' function that runs an XSL processor and collects the
   output;
 - Predefined command line templates and error regexps for Java and
   Windows executable versions of both XT and Saxon;
 - Font lock highlighting so that the important information stands
   out;
 - `xsl-complete' function for inserting element and attribute names;
 - `xsl-insert-tag' function for inserting matching start- and
    end-tags;
 - Automatic completion of end-tags;
 - Automatic indenting of elements with user-definable indentation
   step;
 - `xsl-if-to-choose' converts <xsl:if> to <xsl:choose> with
   nested <xsl:when>; and
 - Comprehensive abbreviations table to further ease typing.