Issue 5163 - Reduce the use of FilterPtr

include/AdblockPlus/FilterEngine.h

Index: include/AdblockPlus/FilterEngine.h
===================================================================
--- a/include/AdblockPlus/FilterEngine.h
+++ b/include/AdblockPlus/FilterEngine.h
@@ -134,17 +134,17 @@
      * @param value JavaScript subscription object.
      */
     Subscription(JsValue&& value);
   };
 
   /**
    * Shared smart pointer to a `Filter` instance.
    */
-  typedef std::shared_ptr<Filter> FilterPtr;
+  typedef std::unique_ptr<Filter> FilterPtr;
 
   /**
    * Shared smart pointer to a `Subscription` instance.
    */
   typedef std::shared_ptr<Subscription> SubscriptionPtr;
 
   /**
    * Main component of libadblockplus.
@@ -280,30 +280,30 @@
     bool IsFirstRun() const;
 
     /**
      * Retrieves a filter object from its text representation.
      * @param text Text representation of the filter,
      *        see https://adblockplus.org/en/filters.
      * @return New `Filter` instance.
      */
-    FilterPtr GetFilter(const std::string& text) const;
+    Filter GetFilter(const std::string& text) const;
 
     /**
      * Retrieves a subscription object for the supplied URL.
      * @param url Subscription URL.
      * @return New `Subscription` instance.
      */
     SubscriptionPtr GetSubscription(const std::string& url) const;
 
     /**
      * Retrieves the list of custom filters.
      * @return List of custom filters.
      */
-    std::vector<FilterPtr> GetListedFilters() const;
+    std::vector<Filter> GetListedFilters() const;
 
     /**
      * Retrieves all subscriptions.
      * @return List of subscriptions.
      */
     std::vector<SubscriptionPtr> GetListedSubscriptions() const;
 
     /**