SciDAVis - Improvements SVN-temp

- Documented classes Fit and Folder.
- Documented some recently-added methods.
- Improved and clarified some existing documentation; in particular, emphasized
the move from 1-based to 0-based indices in new APIs.

- Fixed building with searching for updates enabled. Thanks to Miquel Garriga for spotting this.

- Added changing of the active folder to Python API, allowing scripts to add MDIWindows to arbitrary folders.

- Added command-line option for debug/release build selection.

- Made creation of subfolders available to Python scripts. The method is
meant to be forward-compatible to future SciDAVis versions built entirely
on top of AbstractAspect: folder.addChild(Folder("subfolder")).

- Fixed bug #2894751 (Column mix up in formula when underscore in name).

- Fixed bug #2979848 (Converting a curve between lines/points and bars broken).

- Fixed bug #2982928 (Scidavis crashes at Polynomical Fit) by making sure that
the interval Filter operates on is normalized.

- Removed files with unclear license. Removed code was used only for
Savitzky-Golay smoothing.
- Reimplemented Savitzky-Golay smoothing from scratch, based on information
found at http://www.statistics4u.info/fundstat_eng/cc_filter_savgol_math.html
and routines provided by the GSL. The new implementation features improved
handling of values near the endpoints of the input data; namely, instead of
effectively zero-padding the data, the smoothing polynomial obtained from a
fixed window is used to compute the output values in question.

- Replaced news import via deprecated and broken SF.net interface with a simple RSS adapter.