SciDAVis - Improvements SVN-temp

- Added support for evaluating mathematical expressions and executing scripts using the Python interpreter on Linux and Mac OS X. Scripts can be edited and executed via Note windows or using a script window (which can be launched via a handy shortcut: F3). As soon as the port to Qt4 is ready, these features will be also available on Windows.
- Completely rewritten all fit routines in order to make them available to the scripting interface. Now fit routines support weighting and their output is highly customizable: the user may choose to define the resulting fit curves as mathematical expressions (normal functions) or via a data set.
- Improved the Non-linear Fit dialog.
- Improved the Help Browser. A much improved version of the manual is now available online (thanks to Roger Gadiou).
- Fixed bugs causing crashes during Multi-Peak Fits and other analysis operations.
- Improved saving and restoring of user global settings, including saving of ASCII import options.
- Fixed crash occuring when deleting multiple table rows.
- Improved behaviour of column/row headers in tables/matrices.
- Added new symbols to 2D plot curves.
- Added an Origin-like title bar menu for the MDI windows.