Fixed a bug in the node class destructor. The internal thread was killed but not destroyed.

include/iri_base_driver/iri_base_driver_node.h

@@ -383,6 +383,7 @@ IriBaseNodeDriver<Driver>::~IriBaseNodeDriver()
   
   this->driver_.close();
   this->thread_server_->kill_thread(this->main_thread_id_);
+  this->thread_server_->delete_thread(this->main_thread_id_);
 }
 
 }