SciDAVis - Improvements SVN-temp

- Fixed exporting of ScriptEdit to ASCII files.

- extended 'testprog' to display all possible types of columns

- improved handling of [Return] in TableView
- inverted the behavior of the validity attribute:
now valid is the default for any row and you use
setInvalid()/isInvalid(). Since rows are rarely
invalid, this seemed the better choice.
- removed validityChanged()/validityAboutToChange()
from AbstractDataSource.
Use dataChanged()/dataAboutToChange() instead.
- some small improvements to other classes

- Added LegendMarker and ApplicationWindow::renameWindow() to Python scripting interface.
- Fixed a bug in restoring of Notes from project files.
- Improved ScriptEdit (only plain text copy/paste allowed)

- AbstractFilter and AbstractSimpleFilter improved.
- Tried to make type conversion filters more readable.
- DateTime2StringFilter works around bug in QDate::toString().
- Added conversion filters Double2DayOfWeek, Double2Month, DayOfWeek2Double
and Month2Double.
- StatisticsFilter checks for validity and shows slightly better performance.
- Unit tests compile separately and have better error reporting.

Implemented feature request #002305: Inserting like in Origin.

- minor fix in TableModel

- improved copy routines for double and datetime columns
- fixed flags() in ReadOnlyTableModel
- added missing reading functions in AbstractDateTimeDataSource
that got lost when merging Knut's changes
- fixed all compiling errors of filtertest

- merged my changes with Knut's
- modified the test program to work with the current
TableModel, TableView and the data sources
Status of the test program: It works so far, but
only with string columns

- Data sources are now type safe, that is, there's no implicit conversion
between double, QString and QDateTime any more. This means you have to
cast AbstractDataSource to its subclasses before you can read the actual
data.
- Added conversion filters DateTime2Double, DateTime2String, Double2DateTime
and String2DateTime based on the prior code for implicit conversion.
Filters for month and day based conversion yet to do. Need to investigate
two failing unit tests.
- Added automatic type conversion to ReadOnlyTableModel.
- Fixed some bits in TableModel.
- Filter test program demonstrates a basically working edit->filter->display
chain; some things still need to be fixed, though.
- Some small improvements to filters and their documentation.