stop scrubbing important info from math tags

applications/docx-extract/scrub.xsl

@@ -4,6 +4,7 @@
   xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
   xmlns:xs="http://www.w3.org/2001/XMLSchema"
   xmlns="http://www.w3.org/1999/xhtml"
+  xmlns:math="http://www.w3.org/1998/Math/MathML"
   xpath-default-namespace="http://www.w3.org/1999/xhtml"
   exclude-result-prefixes="#all">
 
@@ -60,6 +61,12 @@
   <!-- Matching b, i and u if they have only whitespace text content w/ other formatting properties
        this includes <b> </b> and <b><tab/></b> -->
 
+  <!-- copy all descendents of math tags unchanged, as they contain info for xsweet_tei_omml2mml.xsl -->
+  <xsl:template match="math:*//*" priority="15">
+    <xsl:copy>
+      <xsl:apply-templates select="node() | @*"/>
+    </xsl:copy>
+  </xsl:template>
 
   <xsl:template priority="5" match="img | br | hr">
     <xsl:copy>