1) Incremental plots

IncrementalPlot shows an example how to implement a plot that
displays growing data. 

The example produces random data when you push the start button.
With 'Timer' you can adjust the intervall between the
the generation of the points, with 'Points' you can set the number
of points to be generated.


2) Stacked Zooming with scrollbars

ScrollZoomer adds scrollbars for zooming. There are a couple of
reasons why the implementation is a hack and therefore the class
is not part of the Qwt lib, but it should be working with all
types of QwtPlots. Who likes to use it can copy the code of
scrollbar.[h|cpp] and scrollzoomer.[h|cpp] to his application.

Uwe
