[ANN] Qwt 6.0.0

With almost one year delay the next stable version of Qwt has been released.

Qwt 6.0 is intendend to run with Qt versions >= Qt 4.4 on all platforms, where
Qt is available.

Because of dropping Qt3 support Qwt 6.0.0 has many API changes, what was an
opportunity for me to clean up many other APIs together with it. So be
prepared, that porting an Qwt 5 application to Qwt 6 might take some time.

Have fun,
Uwe

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Here is a log listing many of the changes:

1) Qt3 support dropped
2) QwtPlot layout/render code ported from int to double
Exported/printed documents in scalable formats like SVG or PDF
are 100% scalable now.
3) Template base classes introduced for curve and curve data
to be reusable in all plot items displaying series of samples.
4) New plot items
- QwtPlotHistogram
- QwtPlotIntervalCurve ( error bars or displaying the area between 2 curves
)
- QwtPlotSpectroCurve ( mapping the z value to a color )
5) Raster items
- QwtMatrixRasterData introduced
- More accurate rendering
- Several API changes
- Thread support for rendering spectrograms
6) QwtPlot::print moved to QwtPlotRenderer
7) Other new classes
QwtColumnSymbol
QwtDoublePoint3D
QwtIntervalSymbol
QwtPlotDirectPainter
QwtSamplingThread
QwtSystemClock
8) QwtPicker and friends reorganized,
QwtPickerTrackerMachine added for displaying a rubberband for
mouse moves. Enter/Leave added to events, that are handled
by the picker machines.
9) QwtScaleWidget::LayoutFlag added
Introduced to control the direction of vertical axis titles.
10)QwtWeedingCurveFitter added
QwtWeedingCurveFitter is an implementation of the Douglas/Peuker
algorithm, that can be used to reduce the number of curve points.
It can be very useful to improve the performance of painting
curves of many lines ( f.e. by implementing different level of details ).
11)Legend code update for representing different pixmaps for different
types of plot items.
12)Copy operators removed, using pointers instead
13)QwtPolarPoint from qwtpolar added
14)QwtThermo
Optional QwtColorMaps added
15)Interfaces and code of all sliders/dials cleaned up.
QApplication::globalStrut(), styled backgrounds ...