Add wallpaper theme

src/main/java/org/tasks/themes/ThemeBase.java

@@ -11,7 +11,8 @@ public class ThemeBase {
     public static final int[] THEMES = new int[] {
             R.style.LightOverride,
             R.style.BaseBlack,
-            R.style.DarkOverride
+            R.style.DarkOverride,
+            R.style.Wallpaper
     };
 
     private final String name;

src/main/res/values/arrays.xml

@@ -84,6 +84,7 @@
         <item>@string/theme_light</item>
         <item>@string/theme_black</item>
         <item>@string/theme_dark</item>
+        <item>@string/theme_wallpaper</item>
     </string-array>
 
     <string-array name="colors">

src/main/res/values/strings.xml

@@ -882,6 +882,7 @@ File %1$s contained %2$s.\n\n
   <string name="theme_dark_grey">Dark Grey</string>
   <string name="theme_light">Light</string>
   <string name="theme_dark">Dark</string>
+  <string name="theme_wallpaper">Wallpaper</string>
   <string name="default_value">Default</string>
 
   <string name="sync_interval_disable">disable</string>

src/main/res/values/theme_base_dark.xml

@@ -33,4 +33,11 @@
         <item name="icon_tint">@android:color/white</item>
     </style>
 
+    <style name="Wallpaper" parent="DarkOverride">
+        <item name="android:windowBackground">@color/black_38</item>
+        <item name="asContentBackground">@color/black_38</item>
+        <item name="android:windowShowWallpaper">true</item>
+    </style>
+
+
 </resources>