change JavaScriptEngine to LoopBasedJavaScriptEngine

Everything works like Node.js. loop() will not need be called explicitly any more.
Including some changes:
* Every thread of script has a looper.
* Use a servant thread in gestures functions of GlobalActionAutomator and image available listener of ScreenCapture.
* For keeping events key and touch listener alive, add Loopers.waitWhenIdle to control whether or not Looper should quit when it has nothing to do

app/src/main/java/com/stardust/scriptdroid/ui/main/MainActivity.java

@@ -292,6 +292,12 @@ public class MainActivity extends BaseActivity implements OnActivityResultDelega
         mDrawerHeaderBackgroundSaver.select(this, mActivityResultMediator);
     }
 
+    @Override
+    protected void onPause() {
+        super.onPause();
+        stopService(new Intent(this, DownloadService.class));
+    }
+
     @Override
     protected void onResume() {
         super.onResume();
@@ -477,6 +483,11 @@ public class MainActivity extends BaseActivity implements OnActivityResultDelega
         EventBus.getDefault().unregister(this);
     }
 
+    @NonNull
+    @Override
+    public OnActivityResultDelegate.Mediator getOnActivityResultDelegateMediator() {
+        return mActivityResultMediator;
+    }
 
     public static void onRecordStop(Context context, String script) {
         Intent intent = new Intent(context, MainActivity_.class)
@@ -488,11 +499,5 @@ public class MainActivity extends BaseActivity implements OnActivityResultDelega
         context.startActivity(intent);
     }
 
-    @NonNull
-    @Override
-    public OnActivityResultDelegate.Mediator getOnActivityResultDelegateMediator() {
-        return mActivityResultMediator;
-    }
-
 
 }

app/src/main/java/com/stardust/scriptdroid/ui/main/SideMenuFragment.java

@@ -44,7 +44,6 @@ import java.util.concurrent.Executor;
 @EFragment(R.layout.fragment_side_menu)
 public class SideMenuFragment extends android.support.v4.app.Fragment {
 
-
     public static void setFragment(FragmentActivity activity, int viewId) {
         SideMenuFragment fragment = new SideMenuFragment_();
         activity.getSupportFragmentManager().beginTransaction().replace(viewId, fragment).commit();