fix epub; requires two custom params

mksupport-common/xsl/epub.xsl

@@ -1,25 +1,8 @@
 <?xml version="1.0"?>
-<!--
-  Generates EPUB XHTML documents from DocBook XML source using DocBook XSL
-  stylesheets.
-
-  NOTE: The URL reference to the current DocBook XSL stylesheets is
-  rewritten to point to the copy on the local disk drive by the XML catalog
-  rewrite directives so it doesn't need to go out to the Internet for the
-  stylesheets. This means you don't need to edit the <xsl:import> elements on
-  a machine by machine basis.
--->
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
-<xsl:import href="http://docbook.sourceforge.net/release/xsl/current/epub/docbook.xsl"/>
+  <xsl:import href="http://docbook.sourceforge.net/release/xsl/current/epub/docbook.xsl"/>
   <xsl:import href="html/common-html.xsl"/>
-  <!--
-DocBook XSL 1.75.2: Nav headers are invalid XHTML (table width element).
-Suppressed by default in Docbook XSL 1.76.1 epub.xsl.
--->
   <xsl:param name="suppress.navigation" select="1"/>
-  <!--
-DocBook XLS 1.75.2 doesn't handle TOCs
--->
   <xsl:param name="generate.toc">
     <xsl:choose>
       <xsl:when test="/article">