Closes #1 - New ArrayReporter, each index is the line number.

Due to how phpcheckstyle works, the output can be slightly weird:

```php
$style = new PHPCheckstyle($formats, $resultDir, $configFile, null, false, true);
$results = $style->processFiles($sources, $options['exclude']);
echo "<pre>".print_r($results, TRUE)."</pre>";
```

So now `$results` is equal to:

```php
Array
(
    [0] => Array
        (
            [1] => Array
                (
                    [0] => Array
                        (
                            [line] => 1
                            [check] => mandatoryHeader
                            [message] => Mandatory header not found.
                            [level] => warning
                        )

                    [1] => Array
                        (
                            [line] => 1
                            [check] => mandatoryHeader
                            [message] => Mandatory header not found.
                            [level] => warning
                        )

                    [2] => Array
                        (
                            [line] => 1
                            [check] => mandatoryHeader
                            [message] => Mandatory header not found.
                            [level] => warning
                        )
/// ....
```

Potentially every Reporter is able to return something in the `stop` method.