Improve title readability against light background

Especially for wide cover images (CDs etc.), the title in white font is barely or not at all
discernible if the cover image is predominantly white or heavily patterned. A black font shadow
greatly improves readability in such cases.

opacclient/opacapp/src/main/res/values/styles_opacapp.xml

@@ -71,6 +71,8 @@
 
     <style name="TextAppearance.Opacapp.ExpandedMediaTitle" parent="TextAppearance.AppCompat.Widget.ActionBar.Title">
         <item name="android:textSize">26sp</item>
+        <item name="android:shadowRadius">15</item>
+        <item name="android:shadowColor">@android:color/black</item>
     </style>
 
     <style name="ThemeOverlay.Opacapp.ActionBar"
@@ -116,4 +118,4 @@
         <item name="android:layout_marginTop">8dp</item>
     </style>
 
-</resources>
+</resources>