allow only one instance of Robot36

app/src/main/AndroidManifest.xml

@@ -12,6 +12,7 @@
         <activity
             android:configChanges="keyboardHidden|orientation|screenSize"
             android:name="xdsopl.robot36.MainActivity"
+            android:launchMode="singleTask"
             android:label="@string/app_name" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />