Allow templates postEvent() calls to also pass parameters. For example this is done in the twig template:
```
{{ postEvent("Template.jsGlobalVariables", minDateYear, maxDateYear) }}
```
and you can hook on this event, by doing:
```
    public function addTrackingHostnamesToJs(&$out, $minDateYear, $maxDateYear)
    {
        // printout out the data as a comment for testing
        $out .= "/* " . $minDateYear . " - " . $maxDateYear . " */";
```