Draw a progression bar
winId=progressionbar(mes)
progressionbar(winId[,mes])
:mes string, message to display. : :winId integer greater than 0, window identificator. :
progressionbar(mes) create a new progression bar, return window identificator.
progressionbar(winId[,mes]) update the progression bar identificated as winId.
winId=progressionbar('Do something');
`realtimeinit`_(0.3);
for j=0:0.1:1,
`realtime`_(3*j);
progressionbar(winId);
end
`winclose`_(winId);