SciDAVis - Improvements SVN-temp

- Fixed encapsulation breaches in AbstractAspect - only undo-aware methods
should be exposed. This does mean that Table has to be careful about not
triggering calls into the AbstractAspect API within its undo commands, but
it (hopefully) makes the undo system more robust.
- Removed #includes <QXmlStreamReader> and <QXmlStreamWriter> from
AbstractAspect.h, since it will be included quite often (directly or
indirectly), not always in conjunction with XML handling.

- fixed problems with context menus by integrating
the QMdiWindow functionality in a class AspectView which
will be the base class of all views that are to be
display in the mdi area
- Table and TableView are not aware of each other which
solves some more problems with passing information or
events up and down the aspect hierarchy (this is a
move away from the MVC to the MVP paradigm)
- fixed the crash when adding columns to a Table
- the options tabs are now properly notified when
an aspect name or comment changes
- still TODO: fix context menu when clicking on
the headers (coordinate mismatch in
TableView::contextMenuEvent())

Added some missing casts (scidavis_temporary.pro demo compiles again).

- improved the project file to tell the application
where the translations and the python stuff is
installed (closes feature request #1887021)

- added make target pdf

- small update to the web page

- new almost complete Russian translation by f0ma

- tagging version 0.1.2

- prepared everything for release 0.1.2

- fixed bug 1868236: Crash when changing the line representation
- fixed crash when plotting an empty table