Represent the extension "saxon", configured with "saxon.xml".
The extension descriptor "saxon.xml" must be at the root of the package. Its
format is as following:
<package xmlns="http://saxon.sf.net/ns/expath-pkg">
<jar>dir/file.jar</jar>
<function>org.example.extension.MyFunction</function>
<xslt>
<import-uri>http://example.org/ns/project/style.xsl</import-uri>
<file>stylesheet.xsl</file>
</xslt>
<xquery>
<namespace>http://example.org/ns/project/lib</namespace>
<file>query-lib.xql</file
</xquery>
</package>
The elements "jar", "function", "xslt" and "xquery" are optional, repeatable,
and can appear in any order. The element "jar" links to the JAR files, in
the content directory, to be included in the classpath. The element "function"
register an extension function by using its fully qualified class name. The
class must extends the Saxon class ExtensionFunctionDefinition. If it extends
the EXPath class EXPathFunctionDefinition, the method setConfiguration() will
be called after it has been instantiated. The elements "xslt" and "xquery"
add XSLT stylesheets and XQuery libraries to the package component list. They
are useful when the components are depending on Saxon, like using some Saxon
extension instruction or attribute.