code: public static void init(Context context, int totalTheme, int defaultTheme, @Nullable EventDispatcher dispatcher){
          getInstance().setup(context, totalTheme, defaultTheme, dispatcher);
      }
docs: Init ThemeManager. Should be call in {@link Application#onCreate()}.
  @param context The context object. Should be {#link Application} object.
  @param totalTheme The total theme.
  @param defaultTheme The default theme if current theme isn't set.
  @param dispatcher The {@link EventDispatcher} will be used to dispatch {@link OnThemeChangedEvent}. If null, then use {@link SimpleDispatcher}.