The first few lines of ModX code updated to post 2004 standards

Who wrote this to begin with? I would expect a few issues with the code, but this is beyond bounds! Even pre PHP5, in PHP4 (which is nearly antique by now), one could do this:

```php
$tstart = array_sum(explode(' ', microtime()));
```

But PHP5 shouldn't be an issue, as the ModX docs state that PHP 5.1.2 is required (oh, as long as you don't use 5.1.6...).

/rant