Reactivate widget view tests; update widget previews

android/uhabits-core/src/main/java/org/isoron/uhabits/core/preferences/Preferences.java

@@ -333,6 +333,12 @@ public class Preferences
         return Integer.parseInt(storage.getString("pref_widget_opacity", "255"));
     }
 
+    public void setWidgetOpacity(int value)
+    {
+        storage.putString("pref_widget_opacity", Integer.toString(value));
+    }
+
+
     /**
      * @return An integer representing the first day of the week. Sunday
      * corresponds to 1, Monday to 2, and so on, until Saturday, which is