title: Unmodified files also copied to target directory in inria spoon transformation
body: <p>I have written source code transformation using inria-spoon library. I have the following function in my transformer (which makes sure that my "process" function is invoked only for desired classes):</p>
  
  <pre><code>public boolean isToBeProcessed(CtInterface&lt;?&gt; ctClass) {
          return isProcessible(ctClass);
      }
  </code></pre>
  
  <p>So only desired classes are transformed. But it seems that all the classes are copied from source directory to target directory. I expect only the transformed classes to be copied to target directory.</p>
  
  <p>Is there some configuration OR handling for this in inria-spoon?</p>
  
  <p>Currently I am invoking my transformer via JUnit test case, using following function:</p>
  
  <pre><code>public void testTransform()
      {
          final String[] arguments = { "-i", "E:/input",
                  "-o", "E:/output", "-p",
                  "com.transformer.ClassTransformer",
                  "-c"};
  
          final Launcher launcher = new Launcher();
          launcher.setArgs(arguments);
          launcher.run();
      }
  </code></pre>