SciDAVis - Improvements SVN-temp

- added text import/export to ScriptEdit
- output from "Execute All" now goes to the end of the Note (instead of cluttering up the code)
- changed some user-visible texts referring to Graphs (MultiLayer) as "Plots" for consistency
- fixed a bug in the Python interface

- Reorganized saveSettings()

- Fixed a bug affecting the 2D plot legend after adding/removing curves.
- Fixed crashes in analysis code: FFT, smoothing, filtering and interpolation due to buggy memory deallocation in conjunction with Graph::addResultCurve()
- Reorganized the readSettings() (I must to do the same with saveSettings() )

- Changed method name Fit::setFitCurveParameters() to generateFunction()
- Improved adding new curves to 2D plots.

fixed bug #7910 (Disapperaing of the buttons in the maximized sub-window)

- improved output placement in notes
- Python init file now imports all QtiPlot classes into the global namespace
- fixed a bug in the FFT code (FFT filters crashed)

- Added some more checks to Fit class;
- Added an exportImage(...) and newLegend() functions in the qti.sip file.

- yet another tweak to the context menu of Matrix column/row headers
- added "Recalculate" to Table menu as well as Table's context menu
- added "Add Function" to Graph's context menu
- several bugfixes and improvements to the scripting interface

- Fixed some crashes in the NonLinearFit class when used from a scripting window.
- Improved the Fit API.
- Added some checks to the Graph::removeCurve() method in order to prevent crashes during script sessions.

Added the docbook and html files for the manual written by Roger Gadiou.