Adding feature of selectable color scheme for PDF

* Adding pdf.color.scheme variable.
* Switching color scheme according to pdf.color.scheme variable,
  Acceptable values are now "full-color" for PC/Tablet reader
  and "gray-scale" for lulu.com POD service.

build/build-pdf

@@ -2,6 +2,7 @@
 
 # Interestings options:
 # --opts="-P full.bleed=1" => add crop margins for print PDF for Lulu
+# --opts="-P pdf.color.scheme=gray-scale" => gray scale PDF for Lulu POD service
 # --opts="-V" => verbose mode of dblatex
 # --lang=de-DE => build a translation
 

build/dblatex/config.xsl

@@ -55,9 +55,39 @@
 <xsl:param name="page.margin.top">1.3cm</xsl:param>
 <xsl:param name="page.margin.bottom">1.3cm</xsl:param>
 
+<!-- PDF color scheme
+Acceptable values are
+full-color (default, for PC/Tablet readers),
+gray-scale (for lulu.com POD service),
+-->
+<xsl:param name="pdf.color.scheme">full-color</xsl:param>
+
 <!-- Fonts used -->
 <xsl:param name="xetex.font">
   <xsl:text>% dblatex template xetex.font starts here.&#10;</xsl:text>
+
+  <xsl:text>% $pdf.color.scheme='</xsl:text>
+  <xsl:value-of select="$pdf.color.scheme"/>
+  <xsl:text>'&#10;</xsl:text>
+  <xsl:choose>
+    <xsl:when test="$pdf.color.scheme='gray-scale'">
+      <xsl:text>
+% pdf.color.scheme gray-scale
+\defaultfontfeatures+{
+  Color          = 000000FF,
+}
+</xsl:text>
+    </xsl:when>
+    <xsl:otherwise>
+      <xsl:text>
+% pdf.color.scheme default
+%
+%
+%
+</xsl:text>
+    </xsl:otherwise>
+  </xsl:choose>
+
   <xsl:choose>
     <xsl:when test="/book[@lang='ja-JP']">
       <xsl:text>