title: Symfony2 translation issue
body: <h1>Initial situation</h1>
  
  <p>I fetch the current weekday in my Controller</p>
  
  <pre><code>$dayname = date('l');
  </code></pre>
  
  <p>For translation I have one dedicated translation file only for the weekdays (<code>weekdays.de.yml</code>)</p>
  
  <pre><code>Monday:  Montag
  Tuesday: Dienstag
  # ...
  </code></pre>
  
  <p>Now I pass the PHP variable <code>$dayname</code> to my twig file, so that I could call it there with using the <code>trans</code> filter.</p>
  
  <pre><code>{% trans_default_domain 'weekdays' %}
  {{ dayname|trans }}
  </code></pre>
  
  <p>Easy going, works fine.</p>
  
  <h1>Objective target</h1>
  
  <p>To keep my <code>translations</code> folder tidied up, I want to migrate those <code>weekdays.de.yml</code> into one large single translation file, where I not just organize the weekdays, but all translation elements, e.g. <code>trans.en.yml</code>, <code>trans.de.yml</code> and <code>trans.fr.yml</code>.</p>
  
  <pre><code># trans.en.yml
  # ...
  weekdays:
      monday:  Monday
      tuesday: Tuesday
      # ...
  
  # trans.de.yml
  # ...
  weekdays:
      monday:  Montag
      tuesday: Dienstag
      # ...
  </code></pre>
  
  <p>I now could call the appropriate weekday in my twig file like this, e.g. for Monday:</p>
  
  <pre><code>{% trans_default_domain 'trans' %}
  {{ weekdays.monday|trans }}
  </code></pre>
  
  <p>But how can I pass the <code>$dayname</code> variable to the twig file and chose the weekday from my according translation file?</p>