Lots of code cleanup and improvements after inspection

Load Today tasks in a AsyncTask
Use of plurals instead of string
Menu icons change
No more tasks now displayed in the center of the screen

DoNExt/app/src/main/AndroidManifest.xml

@@ -22,7 +22,6 @@
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <action android:name="android.intent.action.VIEW" />
-
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>