Fix expension of macros in pointers with default values.

For example :

in xsl decl widget_class(%name, *clsname="%nameWidget", match="widget[@type='%name']", mode="widget_class") alias template {
| class `text **clsname` extends Widget{
content;
| }
};

widget_class('Input');

gives now :

<xsl:template match="widget[@type='Input']" mode="widget_class">
<xsl:text>class </xsl:text>
<xsl:text>InputWidget</xsl:text>
<xsl:text> extends Widget{
</xsl:text>
<xsl:text>}
</xsl:text>
</xsl:template>

Without the fix, <xsl:text>InputWidget</xsl:text> would be <xsl:text>%nameWidget</xsl:text>

include yslt.yml2

estylesheet {
    template "/list" cities
        apply "address[name='Meier']" with "me", ".";

    template "address" {
        param "me";

        call "f" with "addresses", "$me/address[name='Schmid'] | .";
    }

    function "f" {
        param "addresses";

        foreach "$addresses"
            city value "city";
    }
}