Fix console window (now not a QDialog)

It now opens and coloses as expected, depending on user
preferences and the status of the various processes involved.
Console window geometry and state are remembered between runs.

gui/MainWindow.h

@@ -116,7 +116,7 @@ slots:
 
 	void on_actionChangeInstLWJGLVersion_triggered();
 
-	void instanceEnded(BaseInstance *instance, int code, QProcess::ExitStatus status);
+	void instanceEnded();
 
 	void on_actionInstanceSettings_triggered();