Automatically add default filter subscription when necessary.

lib/init.js

 require("filterNotifier").FilterNotifier.addListener(function(action)
 {
   if (action === "load")
+  {
+    let {FilterStorage} = require("filterStorage");
+    if (FilterStorage.subscriptions.length == 0)
+    {
+      // No data, must be a new user or someone with corrupted data - initialize
+      // with default settings
+      let {Subscription, DownloadableSubscription} = require("subscriptionClasses");
+      let {Synchronizer} = require("synchronizer");
+      let {Prefs} = require("prefs");
+      let {Utils} = require("utils");
+
+      // Choose default subscription and add it
+      let subscriptions = require("subscriptions.xml");
+      let node = Utils.chooseFilterSubscription(subscriptions);
+      if (node)
+      {
+        let subscription = Subscription.fromURL(node.url);
+        FilterStorage.addSubscription(subscription);
+        subscription.disabled = false;
+        subscription.title = node.title;
+        subscription.homepage = node.homepage;
+        if (subscription instanceof DownloadableSubscription && !subscription.lastDownload)
+          Synchronizer.execute(subscription);
+      }
+    }
+
     _triggerEvent("init");
+  }
 });