I've already changed the `ValidationException` so as not to let the file
and line from the Validator.php [1]. However, one could go even further
when creating more customizations on top of this library, and allowing
to customize the line could be very useful.
What motivated me making this change because it will be handy when I get
back to work on [Assertion][].
[1]: 75a9b8e94f
[Assertion]: https://github.com/Respect/Assertion
Currently, defining translations is quite cumbersome, and the translator
callback is passed to the constructor of multiple classes, which makes
it quite ugly and could make translations inconsistent.
This commit completely changes how translations are done in Validation.
Instead of using a callback, it uses a specific class, and `Validator`
will pass that object through the objects that render the messages.