Update ExternalCommandReceiver.java (#63)

  - target package: `net.fabiszewski.ulogger`

  - target class: `net.fabiszewski.ulogger.ExternalCommandReceiver`

  - action: `net.fabiszewski.ulogger.intent.action.COMMAND`

  - extra: `"command": [command name]`, where command name is one of: `"start logger"`, `"stop logger"`, `"start upload"`, for starting and stopping position logging and starting track data upload to server (in case live tracking is off)

  - extra: `"command": [command name]`, where command name is one of: 

    - `"start logger"` for starting position logging

    - `"start new logger"` for creating a New Track and starting position logging to it 

    - `"stop logger"` for stopping position logging

    - `"start upload"` for starting track data upload to server (in case live tracking is off)

- third party examples:

  - Automate (LlamaLab) – Send broadcast block with `Package`, `Receiver Class` and `Action` fields as above and `Extras` field eg. `{"command": "start logger"}`

  - Tasker (joaomgcd) – System → Send intent. Fields `Action`, `Package`, `Class` as above and `Extra` field eg. `command:start logger`

public class ExternalCommandReceiver extends BroadcastReceiver {

    private static final String START_LOGGER = "start logger";

    private static final String START_NEW_LOGGER = "start new logger";

    private static final String STOP_LOGGER = "stop logger";

    private static final String START_UPLOAD = "start upload";

                    case START_LOGGER:

                        startLoggerService(context);

                        break;

                    case START_NEW_LOGGER:

                        startNewLoggerService(context);

                        break;

                    case STOP_LOGGER:

                        stopLogger(context);

                        break;

    }

    /**

     * Start logger service (new trace)

     * @param context Context

     */

    private void startNewLoggerService(Context context) {

        DbAccess db = DbAccess.getInstance();

        db.open(context);

        db.newTrack(AutoNamePreference.getAutoTrackName(context));

        db.close();

        Intent intent = new Intent(context, LoggerService.class);

        ContextCompat.startForegroundService(context, intent);

    }

    /**

     * Start logger service

     * @param context Context