Have the light theme as the default throughout

It was changed in preferences.xml, but not in the manifest and in the default
case in the Java code.

F-Droid/AndroidManifest.xml

@@ -61,7 +61,7 @@
         android:label="@string/app_name"
         android:description="@string/app_description"
         android:allowBackup="true"
-        android:theme="@style/AppThemeDark"
+        android:theme="@style/AppThemeLight"
         android:supportsRtl="true"
         >
 

F-Droid/src/org/fdroid/fdroid/FDroidApp.java

@@ -110,7 +110,7 @@ public class FDroidApp extends Application {
             case light:
                 return R.style.AppThemeLight;
             default:
-                return R.style.AppThemeDark;
+                return R.style.AppThemeLight;
         }
     }