Use `--stderr` with `--tap` and/or `--testdox`

I don't think this pull request is the best solution for the problem of #1455, but I'm sure it fixes the problem.

Actually, the main problem, IMO, is because there is no centralized point to create printers instances. `PHPUnit_TextUI_Command` creates and configures printers objects but `PHPUnit_TextUI_TestRunner` too. 

I will be glad to create a Factory for these printers but it requires a quite of change.

PS.: I can not test this, because seems that PHPT does not recognize STDERR.
@sebastianbergmann, can I merge the arguments with the settings from configuration? Like:
```php
$this->arguments = $this->arguments + $phpunit;
```