-Added player conversion to background and popup players.

-[#919] Fixed custom notification does not trigger unlocking on lockscreen.
-[#947] Fixes player crashing on internet outage, issue partially addressed.
-Fixed main player losing state after destroy while in background.
-Fixed main player controls not hiding automatically after orientation change.
-Fixed dialog uploader not marqueeing when too long.
-Fixed popup permission throwing NPE on BaseList.
-Refactored popup permissions to start in NavigationHelper.
-Extracted hardcoded string for player menus.
-Bump Java version to 1.8.
-Some lambda conversions.

app/src/main/res/menu/menu_play_queue_bg.xml

@@ -0,0 +1,10 @@
+<menu 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"
+    tools:context="org.schabi.newpipe.history.HistoryActivity">
+
+    <item android:id="@+id/action_switch_popup"
+        android:orderInCategory="1999"
+        android:title="@string/switch_to_popup"
+        app:showAsAction="never"/>
+</menu>