added a loading diaolg, when you change the course & code cleanup

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

@@ -27,7 +27,7 @@
         <FrameLayout
                 android:id="@+id/fragment_container"
                 android:layout_width="match_parent"
-                android:layout_height="match_parent"></FrameLayout>
+                android:layout_height="match_parent"/>
     </LinearLayout>
 
 </androidx.coordinatorlayout.widget.CoordinatorLayout>

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

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+              android:orientation="vertical"
+              android:layout_width="wrap_content"
+              android:layout_height="wrap_content" android:gravity="center" android:paddingBottom="9dp">
+
+    <ProgressBar
+            style="?android:attr/progressBarStyle"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:id="@+id/progressBar"/>
+    <TextView
+            android:text="@string/loading_timetable"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" android:id="@+id/textView2" android:gravity="center"
+            android:textSize="18sp"/>
+</LinearLayout>

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

@@ -2,7 +2,7 @@
 <LinearLayout
         xmlns:android="http://schemas.android.com/apk/res/android"
         xmlns:app="http://schemas.android.com/apk/res-auto"
-        xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
+        android:layout_width="match_parent"
         android:layout_height="@dimen/nav_header_height"
         android:background="@drawable/side_nav_bar"
         android:paddingBottom="@dimen/activity_vertical_margin"

app/src/main/res/values-de-rDE/strings.xml

@@ -18,6 +18,7 @@
     <string name="main_color_desc">Die Primärfarbe, standard ist Indigo</string>
     <string name="select">auswählen</string>
     <string name="about">über</string>
+    <string name="loading_timetable">lade Stundenplan …</string>
     <string name="hello_blank_fragment">bald ™</string>
     <string name="navigation_drawer_close">Navigationsleiste schließen</string>
     <string name="navigation_drawer_open">Navigationsleiste öffnen</string>

app/src/main/res/values-v21/styles.xml

@@ -1,7 +0,0 @@
-<resources>
-    <style name="AppTheme.NoActionBar">
-        <item name="windowActionBar">false</item>
-        <item name="windowNoTitle">true</item>
-        <item name="android:statusBarColor">@android:color/transparent</item>
-    </style>
-</resources>

app/src/main/res/values/strings.xml

@@ -35,11 +35,10 @@
     <string name="version" translatable="false">version 0.1.3</string>
     <string name="about">about</string>
     <string name="about_txtView" translatable="false">hso App by @Seil0</string>
-    <string name="about_text" translatable="false">"This software is made by @Seil0 and is published under the terms and conditions of GPL 3.
-        For further information visit git.mosad.xyz/Seil0/ProjectLaogai © 2018 seil0@mosad.xyz "
-    </string>
+    <string name="about_text" translatable="false">"This software is made by @Seil0 and is published under the terms and conditions of GPL 3. For further information visit \ngit.mosad.xyz/Seil0/ProjectLaogai \n\n© 2018 seil0@mosad.xyz "</string>
+    <string name="loading_timetable">loading timetable …</string>
+
 
     <string name="hello_blank_fragment">soon ™</string>
     <string name="string_new_line" translatable="false">%1$s\n</string>
-
 </resources>

app/src/main/res/xml/backup_descriptor.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<full-backup-content>
+    <!-- Exclude specific shared preferences that contain GCM registration Id -->
+</full-backup-content>