Change launcher flags for single instance of app

Closes #301

src/main/AndroidManifest.xml

@@ -128,7 +128,8 @@
         <!-- Activity that displays task list -->
         <activity
             android:name="com.todoroo.astrid.activity.TaskListActivity"
-            android:windowSoftInputMode="stateHidden|adjustResize">
+            android:windowSoftInputMode="stateHidden|adjustResize"
+            android:launchMode="singleTask" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
@@ -141,8 +142,7 @@
 
         <!-- Activity launched from shortcut -->
         <activity
-            android:name="com.todoroo.astrid.activity.ShortcutActivity"
-            android:clearTaskOnLaunch="true">
+            android:name="com.todoroo.astrid.activity.ShortcutActivity">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.DEFAULT" />
@@ -161,6 +161,7 @@
         </activity>
 
         <!-- Activity launched from ShareLink menu item -->
+        <!-- TODO: clearTaskOnLaunch probable cause of #275 -->
         <activity
             android:name="com.todoroo.astrid.activity.ShareLinkActivity"
             android:clearTaskOnLaunch="true">

src/main/java/com/todoroo/astrid/activity/ShortcutActivity.java

@@ -56,20 +56,25 @@ public class ShortcutActivity extends Activity {
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
-        launchTaskList(getIntent());
+        launchTaskList();
     }
 
     @Override
     protected void onNewIntent(Intent intent) {
         super.onNewIntent(intent);
 
-        launchTaskList(intent);
+        setIntent(intent);
+
+        launchTaskList();
     }
 
-    private void launchTaskList(Intent intent) {
+    private void launchTaskList() {
+        Intent intent = getIntent();
+
         Bundle extras = intent.getExtras();
 
         Intent taskListIntent = new Intent(this, TaskListActivity.class);
+        taskListIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TOP);
 
         if(extras != null && extras.containsKey(TOKEN_CUSTOM_CLASS)) {
             taskListIntent.putExtras(intent.getExtras());

src/main/java/com/todoroo/astrid/activity/TaskListActivity.java

@@ -112,8 +112,27 @@ public class TaskListActivity extends AstridActivity implements OnPageChangeList
         DrawerLayout drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
         navigationDrawer.setUp(drawerLayout);
 
-        initializeFragments();
+        View editFragment = findViewById(R.id.taskedit_fragment_container);
+
+        if(editFragment != null) {
+            fragmentLayout = LAYOUT_DOUBLE;
+        } else {
+            fragmentLayout = LAYOUT_SINGLE;
+        }
+
+        readIntent();
+    }
+
+    @Override
+    protected void onNewIntent(Intent intent) {
+        super.onNewIntent(intent);
+
+        setIntent(intent);
 
+        readIntent();
+    }
+
+    private void readIntent() {
         Bundle extras = getIntent().getExtras();
         if (extras != null) {
             extras = (Bundle) extras.clone();
@@ -218,16 +237,6 @@ public class TaskListActivity extends AstridActivity implements OnPageChangeList
         return BuiltInFilterExposer.getMyTasksFilter(getResources());
     }
 
-    protected void initializeFragments() {
-        View editFragment = findViewById(R.id.taskedit_fragment_container);
-
-        if(editFragment != null) {
-            fragmentLayout = LAYOUT_DOUBLE;
-        } else {
-            fragmentLayout = LAYOUT_SINGLE;
-        }
-    }
-
     @Override
     public boolean onFilterItemClicked(FilterListItem item) {
         TaskEditFragment.removeExtrasFromIntent(getIntent());

src/main/java/org/tasks/widget/WidgetHelper.java

@@ -35,13 +35,14 @@ import java.util.concurrent.TimeUnit;
 import javax.inject.Inject;
 import javax.inject.Singleton;
 
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.content.Intent.FLAG_ACTIVITY_MULTIPLE_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 
 @Singleton
 public class WidgetHelper {
 
-    public static int flags = FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_MULTIPLE_TASK;
+    public static int flags = FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP;
 
     private final TagDataDao tagDataDao;
     private final Preferences preferences;
@@ -105,7 +106,7 @@ public class WidgetHelper {
             Bundle extras = AndroidUtilities.bundleFromSerializedString(serializedExtras);
             listIntent.putExtras(extras);
         }
-        listIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
+        listIntent.setFlags(flags);
         if (filter != null) {
             listIntent.putExtra(TaskListFragment.TOKEN_FILTER, filter);
             listIntent.setAction("L" + widgetId + filter.getSqlQuery());