SciDAVis - Improvements SVN-temp

- Fixed bug in Python interface to LorentzFit.

- Section on Savitzky-Golay smoothing rewritten to provide better background
information on the algorithm. Corrected formula, which contained several
errors.
- Corrected title of FFT smoothing section.

- Added (non-closing) apply button to FunctionDialog.

- Corrected typo in API documentation.

- Reconcidered handling of edges in Savitzky-Golay smoothing.
While the new behaviour arguably does have benefits, the legacy zero-padding
approach isn't strictly wrong. On the whole, changing this between bugfix
releases is probably more annoying than sticking with a slightly inferior
solution (for now).
=> rewritten Savitzky-Golay code changed to use zero padding

- Corrected several technical issues in the manual. Should compile (using Makefile) now.

- Added experimental OPJ import code by Miquel Garriga.

- Deprecated Folder::window(). From a scripting point of view, the method is a
complete mess. Fortunately, it was never documented; and there's findWindow()
which can be used instead.

- Added some information about LabPlot collaboration and related resources to
Contributing/Coding.

- Changed wording of Windows download instructions which looked a bit strange,
considering the age of the released manual.