title: install4j 6.1.6: "Replacement script for language code" doesn't work on MacOS
body: <p>We use install4j for our software and we have different languages for our application and for installer too. We are migrating from install4j 5.1.3 to install4j 6.1.6 . During check of installers we've found that "Replacement script for language code" doesn't work on MacOS. For verification I've just built simple installer that returns just "en" in the replacement script. Manual says that Language Selection Dialog should't be shown it that case, but on MacOS it is shown.
  With log output there is ClassNotFoundException:</p>
  
  <pre><code>[ERROR] java.lang.ClassNotFoundException: com.install4j.script.I4jScript_Internal_7
  java.lang.ClassNotFoundException: com.install4j.script.I4jScript_Internal_7
      at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
      at com.install4j.runtime.installer.helper.Install4jClassLoader.loadClass(Install4jClassLoader.java:81)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
      at java.lang.Class.forName0(Native Method)
      at java.lang.Class.forName(Class.java:348)
      at com.install4j.runtime.installer.ContextImpl.runScript(ContextImpl.java:187)
      at com.install4j.runtime.installer.ContextImpl.runScript(ContextImpl.java:182)
      at com.install4j.runtime.installer.controller.LanguageSelector.initLanguage(LanguageSelector.java:45)
      at com.install4j.runtime.installer.controller.Controller.start(Controller.java:60)
      at com.install4j.runtime.installer.Installer.runInProcess(Installer.java:59)
      at com.install4j.runtime.installer.Installer.main(Installer.java:46)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at com.exe4j.runtime.LauncherEngine.launch(LauncherEngine.java:65)
      at com.install4j.runtime.launcher.MacLauncher.main(MacLauncher.java:67)
  </code></pre>
  
  <p>However, the I4jScript_Internal_7 class is contained in user.jar in archive and it is our script, but for some reason install4j couldn't load it.</p>