Adjust virtual / non virtual for some methods

src/libdanbooru/servicebase.h

@@ -111,7 +111,7 @@ public:
     /**
      * @brief Return the api type of the searvice.
      **/
-    int apiType() const;
+    virtual Danbooru::ApiType apiType() const;
 
     /**
      * @brief Return the blacklisted tags for the service
@@ -152,15 +152,14 @@ public:
 
     /**
      * @brief Move to the next pool page and retrieve new posts associated to the pool.
-     * The default implementation does nothing.
      *
      **/
-    Q_INVOKABLE virtual void nextPoolPage();
+    Q_INVOKABLE void nextPoolPage();
 
     /**
      * @return A QStringList containing the currently-selected tags
      **/
-    QStringList postTags();
+    QStringList postTags() const;
 
     /**
      * @brief Resets the service to the default state, clearing the page counters.