title: Get all available cultures from a .resx file group
body: <p>I need to programatically list the available cultures in a resx file group, but the ResourceManager class doesn't seem to help.</p>
  
  <p>I may have :</p>
  
  <pre><code>Labels.resx
  Labels.fr-FR.resx
  Labels.ro-RO.resx
  </code></pre>
  
  <p>and so on</p>
  
  <p>However, how can I find these three (or how many would there be) cultures at runtime?</p>