XSL transformation / Add support for datatype in xsl:param.

    Before that change all XSL parameters were defined as String and
    XSL conversion may be required for example to convert string to boolean, ...

    With this change, more strict type could be defined in XSLT.
    eg. use as attribute to define the datatype:

      <xsl:param name="setParentIdentifierWithUUIDAttribute"
                 select="true()"
                 as="xs:boolean"/>

    Saxon Java class mapping to XPath type is defined http://www.saxonica.com/documentation/javadoc/net/sf/saxon/Controller.html#setParameter(java.lang.String, java.lang.Object)