SciDAVis - Improvements SVN-temp

- Improved the lineDialog, using a suggestion from an old patch from Knut: coordinates can be now displayed in pixels or in scale coordinates.
- Fixed a table context menu bug and improved (patch from Shen Chen).
- Added the possibility to change the canvas background color.

Still TO DO: fix export to SVG and to EPS!

Almost finished the port to Qwt5: the only thing not working correctly is the EPS export. Testing needed.

-Ported LegendMarker and all derived QwtPlotCurves to Qwt5

-Fixes autoscaling of 2D plots.
-Improves ImageMarker and LineMarker classes: the export to EPS and SVG (only for line markers) of these objects works correctly.
-Adds a first implementation of the feature request #2304: zoom in/zoom out in images is possible now (the number of zoom in operations is limited, I don't know why yet and zooming out only restores the initial state of the image).

Fixed numerical format of axis labels.

improvements to ConfigDialog:
- the width of the itemsList is now calculated
depending on the width of its contents
- "Apply", "Ok", and "Cancel" now work like
commonly used in other applications
(e.g. "Cancel" now cancels all settings
since the last "Apply") with one exception:
the language setting

- merged changes to ConfigDialog from scripting branch
and converted them to Qt4

Fixed more stuff in the the port to Qwt5: set scale division, ticks length.

Fixed the behavior of some of the 2D plot tools: the data reader, the data range selectors, ...