Activity info into Device Card: use correct coordinator method

- use correct DeviceCoordinator method supportsActivityTracking()
- remove placeholders from xml
- clarify comments in DeviceCoordinator
- clean up some previously added unused imports

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/activities/ControlCenterv2.java

@@ -513,7 +513,7 @@ public class ControlCenterv2 extends AppCompatActivity
         protected void doInBackground(DBHandler db) {
             for (GBDevice gbDevice : deviceList) {
                 final DeviceCoordinator coordinator = DeviceHelper.getInstance().getCoordinator(gbDevice);
-                if (coordinator.supportsActivityDataFetching()) {
+                if (coordinator.supportsActivityTracking()) {
                     long[] steps = getSteps(gbDevice, db);
                     deviceActivityHashMap.put(gbDevice.getAddress(), steps);
                 }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/adapter/GBDeviceAdapterv2.java

@@ -41,7 +41,6 @@ import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.cardview.widget.CardView;
-import androidx.fragment.app.FragmentActivity;
 import androidx.localbroadcastmanager.content.LocalBroadcastManager;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -53,8 +52,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.text.DecimalFormat;
-import java.util.Calendar;
-import java.util.GregorianCalendar;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
@@ -69,11 +66,9 @@ import nodomain.freeyourgadget.gadgetbridge.activities.ControlCenterv2;
 import nodomain.freeyourgadget.gadgetbridge.activities.HeartRateDialog;
 import nodomain.freeyourgadget.gadgetbridge.activities.SettingsActivity;
 import nodomain.freeyourgadget.gadgetbridge.activities.VibrationActivity;
-import nodomain.freeyourgadget.gadgetbridge.activities.charts.ActivityListingDashboard;
 import nodomain.freeyourgadget.gadgetbridge.activities.charts.ChartsActivity;
 import nodomain.freeyourgadget.gadgetbridge.activities.devicesettings.DeviceSettingsActivity;
 import nodomain.freeyourgadget.gadgetbridge.activities.devicesettings.DeviceSettingsPreferenceConst;
-import nodomain.freeyourgadget.gadgetbridge.database.DBAccess;
 import nodomain.freeyourgadget.gadgetbridge.database.DBHandler;
 import nodomain.freeyourgadget.gadgetbridge.database.DBHelper;
 import nodomain.freeyourgadget.gadgetbridge.devices.DeviceCoordinator;
@@ -84,7 +79,6 @@ import nodomain.freeyourgadget.gadgetbridge.impl.GBDevice;
 import nodomain.freeyourgadget.gadgetbridge.model.ActivitySample;
 import nodomain.freeyourgadget.gadgetbridge.model.ActivityUser;
 import nodomain.freeyourgadget.gadgetbridge.model.BatteryState;
-import nodomain.freeyourgadget.gadgetbridge.model.DailyTotals;
 import nodomain.freeyourgadget.gadgetbridge.model.DeviceType;
 import nodomain.freeyourgadget.gadgetbridge.model.RecordedDataTypes;
 import nodomain.freeyourgadget.gadgetbridge.util.DateTimeUtils;
@@ -126,7 +120,6 @@ public class GBDeviceAdapterv2 extends RecyclerView.Adapter<GBDeviceAdapterv2.Vi
         }
 
         final DeviceCoordinator coordinator = DeviceHelper.getInstance().getCoordinator(device);
-
         holder.container.setOnClickListener(new View.OnClickListener() {
 
             @Override
@@ -630,7 +623,7 @@ public class GBDeviceAdapterv2 extends RecyclerView.Adapter<GBDeviceAdapterv2.Vi
                                                                  }
                                                              }
         );
-        if (coordinator.supportsActivityDataFetching()) {
+        if (coordinator.supportsActivityTracking()) {
             setActivityCard(holder, device, dailyTotals);
         }
     }

app/src/main/java/nodomain/freeyourgadget/gadgetbridge/devices/DeviceCoordinator.java

@@ -143,6 +143,8 @@ public interface DeviceCoordinator {
     /**
      * Returns true if activity data fetching is supported by the device
      * (with this coordinator).
+     * This enables the sync button in control center and the device can thus be asked to send the data
+     * (as opposed the device pushing the data to us by itself)
      *
      * @return
      */
@@ -151,6 +153,7 @@ public interface DeviceCoordinator {
     /**
      * Returns true if activity tracking is supported by the device
      * (with this coordinator).
+     * This enables the ChartsActivity.
      *
      * @return
      */

app/src/main/res/layout/device_itemv2.xml

@@ -502,7 +502,7 @@
                             android:layout_width="match_parent"
                             android:layout_height="wrap_content"
                             android:gravity="center_vertical|center_horizontal"
-                            android:text="59999"
+                            android:text=""
                             android:textSize="18sp" />
 
                         <ProgressBar
@@ -542,7 +542,7 @@
                             android:layout_width="match_parent"
                             android:layout_height="wrap_content"
                             android:gravity="center_vertical|center_horizontal"
-                            android:text="1"
+                            android:text=""
                             android:textSize="18sp" />
 
                         <ProgressBar
@@ -581,7 +581,7 @@
                             android:layout_width="match_parent"
                             android:layout_height="wrap_content"
                             android:gravity="center_vertical|center_horizontal"
-                            android:text="300"
+                            android:text=""
                             android:textSize="18sp" />
 
                         <ProgressBar