GH-1389 wrap QDesktopServices and QProcess::startDetached

Essentially do not pass some environment variables to subprocesses:
* LD_PRELOAD
* LD_LIBRARY_PATH
* LD_DEBUG
* QT_PLUGIN_PATH
* QT_FONTPATH

application/MainWindow.h

@@ -166,9 +166,6 @@ private:
 	void finalizeInstance(InstancePtr inst);
 	void launch(InstancePtr instance, bool online = true, BaseProfilerFactory *profiler = nullptr);
 
-	/// open a web page in the default browser
-	void openWebPage(QUrl url);
-
 private:
 	std::unique_ptr<Ui> ui;