* Add style sheets for a native look of JavaFX-based views such that the
  UI does not break too much in comparison to the SWT-based views.
* Windows 8/10, Windows 7, and MacOS X are supported. For Linux (GTK/QT)
  no style sheets have been found at the creation time of this commit.
* The style sheets for the Windows 7 and the MacOS look are bundled in
  jars that define additional controls for animation etc. These libs
  are not usable with the SWT/JavaFX integration layer since it is
  impossible to load the control classes defined in the CSS file. The
  reason for this resides in the special classloader architecture of the
  JavaFX/SWT integration where it is impossible to inject classes into
  the classloader hierarchy without modifying e(fx)clipse plugins, or
  writing custom classloader/wrapper plugins for osgi.
* The licenses of the imported CSS files are 2- and 3-clause BSD
  licenses which are placed in the folders containing the CSS files.

Issue-Ref: 3209
Issue-Url: https://af3-developer.fortiss.org/issues/3209


Signed-off-by: Alexander Diewald <diewald@fortiss.org>