Add QAspectRatioLayout borrowed from http://wiki.forum.nokia.com/index.php/CS001309_-_Maintaining_square_form_for_a_widget_in_Qt to maintain width == height * 2 aspect ratio for map drawing widget

#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}