Replaced the code to substitute host address part in URL

with libcurl library calls. This solution should be more robust
than a homebrew URL parser solution.

src/slic3r/GUI/Plater.cpp

@@ -2219,6 +2219,7 @@ Plater::priv::~priv()
 {
     if (config != nullptr)
         delete config;
+    // Saves the database of visited (already shown) hints into hints.ini.
     notification_manager->deactivate_loaded_hints();
 }