Disable TorPlugin before applying changed settings

The is necessary for two reasons:

1. Since Tor 0.3.4.8, it doesn't reconnect when changing the value of
   UseBridges via the control connection without also resetting
   DisableNetwork
2. The TorPlugin needs to set itself to a disconnected state for the UI
   to properly reflect this new state

Fixes #1420

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -627,6 +627,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			if (s.getNamespace().equals(ID.getString())) {
 				LOG.info("Tor settings updated");
 				settings = s.getSettings();
+				// Works around a bug introduced in Tor 0.3.4.8. Could be
+				// replaced with callback.transportDisabled() when fixed.
+				disableNetwork();
 				updateConnectionStatus(networkManager.getNetworkStatus());
 			}
 		} else if (e instanceof NetworkStatusEvent) {
@@ -634,6 +637,16 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		}
 	}
 
+	private void disableNetwork() {
+		connectionStatusExecutor.execute(() -> {
+			try {
+				enableNetwork(false);
+			} catch (IOException ex) {
+				logException(LOG, WARNING, ex);
+			}
+		});
+	}
+
 	private void updateConnectionStatus(NetworkStatus status) {
 		connectionStatusExecutor.execute(() -> {
 			if (!running) return;