Fixed context menus not working in the editor (fixes #2183)

Turns out after moving the menu handling to right-button-up, I didn't add a call to the base
method here, which meant the show-context-menu code was never called.

src/editor/controller/editor_controller.cpp

@@ -1348,8 +1348,11 @@ void editor_controller::right_drag_end(int x, int y, const bool /*browse*/)
 	perform_delete(a);
 }
 
-void editor_controller::right_mouse_up(int x, int y, const bool /*browse*/)
+void editor_controller::right_mouse_up(int x, int y, const bool browse)
 {
+	// Call base method to handle context menus.
+	mouse_handler_base::right_mouse_up(x, y, browse);
+
 	editor_action* a = get_mouse_action().up_right(*gui_, x, y);
 	perform_delete(a);
 	if (a) set_button_state();