I'm turning into the resident XSLTmonk.

Feed this stylesheet into whichever XSLT processor is handy, along with your file:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Tr
+ansform">

<xsl:output method="text" encoding="us-ascii" />

</xsl:stylesheet>
[download]

This is minimal because in your case the XSLT processor defaults (recurse full tree, printing text nodes) are a perfect fit.

For some Perl code driving an XSL transform, see my example elsewhere from earlier today: Re: MathML 2 ascii?. But if you can install those modules you probably have a commandline XSLT processor installed anyway.

Makeshifts last the longest.