title: Class 'Slim\Slim' not found with composer
body: <p>I want to use Slim 3 in a subdirectory, but cannot seem to load it. All files are contained in the subdirectory, including composer.json. Here is my composer.json:</p>
  
  <pre><code>"require": {
      "slim/slim": "3.0.0-RC1"
  }
  </code></pre>
  
  <p>Here is my script:</p>
  
  <pre><code>&lt;?php
  require "vendor/autoload.php";
  use \Slim\Slim;
  
  $app = new \Slim\Slim();
  $app-&gt;get('/subdirectory/hello/:name', function ($name) {
      echo "Hello, $name";
  });
  $app-&gt;run();
  </code></pre>
  
  <p>I tried many things, including <a href="https://stackoverflow.com/questions/28126614/class-slim-not-found-when-installing-slim-with-composer">Class Slim not found when installing slim with composer</a> and <a href="https://stackoverflow.com/questions/22369302/php-fatal-error-class-slim-not-found">PHP Fatal error: Class &#39;Slim&#39; not found</a>. Unfortunately, they didn't solve my problem.</p>
  
  <p>The error I get is <code>Fatal error: Class 'Slim\Slim' not found in ... on line 5</code>, which corresponds to <code>$app = new \Slim\Slim();</code>.</p>
  
  <p>Anyone know what I'm missing?</p>