DBDriver: when an empty database url is provided, an empty database "in memory" is used by default. Tango: fixed second database not recorded in Data Recorder mode (now creating a new one on save). Mapping parameters are saved in database instead of the one used to record data (Data Recorder mode).

app/android/jni/jni_interface.cpp

@@ -55,6 +55,13 @@ Java_com_introlab_rtabmap_RTABMapLib_onCreate(
 	return app.onCreate(env, activity);
 }
 
+JNIEXPORT void JNICALL
+Java_com_introlab_rtabmap_RTABMapLib_openEmptyDatabase(
+    JNIEnv* env, jobject)
+{
+	return app.openDatabase();
+}
+
 JNIEXPORT void JNICALL
 Java_com_introlab_rtabmap_RTABMapLib_openDatabase(
     JNIEnv* env, jobject, jstring databasePath)