code: public static boolean createAndLaunchWorld(WorldSettings worldsettings, boolean isTemporary)
      {
          String s = getNewSaveFileLocation(isTemporary);
          Minecraft.getMinecraft().launchIntegratedServer(s, s, worldsettings);
          cleanupTemporaryWorlds(s);
          return true;
      }
docs: Creates and launches a unique world according to the settings.
  @param worldsettings the world's settings
  @param isTemporary if true, the world will be deleted whenever newer worlds are created
  @return