JDK8, lint fixing (#2888)

* Use Kotlin JDK8

* Satisfy a ton of lints

* Run res/layout files (and manifest) through reformatter

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

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:tools="http://schemas.android.com/tools"
     xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="wrap_content">
 
@@ -18,6 +18,6 @@
         android:layout_centerHorizontal="true"
         android:layout_gravity="end"
         app:fastScrollerBubbleEnabled="false"
-        tools:visibility="visible"/>
+        tools:visibility="visible" />
 
 </FrameLayout>