Fix #1516: fixed scrolling library menu in landscape mode

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

@@ -2,7 +2,10 @@
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+            android:layout_width="fill_parent"
+            android:layout_height="fill_parent" >
+<LinearLayout
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
@@ -75,3 +78,5 @@
         app:listItemIcon="@drawable/library_icon_history_circle_background"
         app:listItemTitle="@string/library_history" />
 </LinearLayout>
+</ScrollView>
+