SciDAVis - Improvements SVN-temp

- Eliminated some crashes and cases of "Couldn't change the axis type to the
requested format" when working with date/time axis labels.

- Documented class ApplicationWindow.
- Documented recently added methods MDIWindow.clone(), Graph.layers() and
Layer.curves().
- Documented the slightly unintuitive way in which symbols, brushes and pens
need to be updated in Qwt.

- Added methods Graph.layers() and Layer.curves() (handy for iterating).

Fixed and improved various parts of the Python API:
- Added MDIWindow.clone(), which is supposed to replace ApplicationWindow.clone().
It's more natural to ask the window for a copy of itself; besides, this should
be easier to learn because you do not have to remember about the global "app"
variable.
- Added Folder.save(), which is supposed to replace ApplicationWindow.saveFolder().
It's more natural to ask the folder to save itself; besides, this should
be easier to learn because you do not have to remember about the global "app"
variable.
- Fixed Graph.addLayer() to call ApplicationWindow::setPreferences() on the new
layer. Having to do this manually is just insane. This deprecates th export of
setPreferences().
- Calling Note.execute() or Note.executeAll() apparently does not work correctly.
Added comment stating the problem; for now, we'll just leave the methods
undocumented and tell users to work around the issue using exec(). It's not
quite clear to me whether calling C++ -> Python -> C++ -> Python again can
in principle be made to work correctly at all.
- Fixed ApplicationWindow.newTable(name) to silently rename the table in case of
a name conflict. A popup is just not what one usually wants in a
batch-processing script; and if really needed, the conflict can easily be
detected by checking the .name() of the created table.
- Added ApplicationWindow.newGraph(name) for consistency with newTable(),
newMatrix() and newNote().
- Fixed ApplicationWindow.plot() to apply the indicated color to all created
curves, including their symbols, as one would expect.

- Documented class Note.

- Documented class Graph.

- Corrected typo in Python API.
- Added backwards-compatibility methods Graph.setAlignement() and
Graph.arrangeLayers(bool,bool); just in case anyone was using them
(even though they were undocumented).

- Sanitized Python interface to layer arrangement.
- Renamed Graph.print() to Graph.printDialog(), since print is a reserved word in Python.

- Made documentations of math functions exported to muParser translatable.
- Lupdate'd all translations.
- Added missing texts to German translation.

- Added some missing result defaults in hand-written API code.
- Added methods Layer.setRightTitle() and Layer.setTopTitle().
- Renamed Layer.print() to Layer.printDialog(), because print is a reserved word
in Python; so the method couldn't be called previously.