#11 AsyncTasks will be deprecated for API Levels 30 and over

Usage of `AsyncTask` will be deprecated for API levels 30 and over. Must substitute for some other background task manager class such as `Executor`, `ThreadPoolExecutor` and `FutureTask` from the `java.util.concurrent` package. This affects all the `uprrp.tania.networking` package files. [More info here](https://developer.android.com/reference/android/os/AsyncTask). Might be postponed for some time, since I rewrote these files to avoid Context leaks, exception swallowing and other nuisances...