fixed:
  * OpenGL setting value 'blend' was never reflected in preferences dialog
  * Booked ATC dialog set wrong date and did not show booked stations
    (https://sourceforge.net/p/qutescoop/tickets/5/)
  * ignore wind data that contains only 0's
  * prevent access to non-initialized wind stations
 added:
  * when zooming through right or left double click, the cursor is moved to the
    map position on which the zoom in/out was just initiated
  * wind arrows have a darker background for readability
  * the popup window at program start (aka 'Launcher') won't wait until Whazzup- or
    wind data is fully downloaded but load the map right away
  * weather data download shows a progressbar - we will need to integrate the UI for
    simultaneous downloads better, though
  * this changelog is now accessible from the menu
 changed:
  * wind arrows UI: changed appeareance for better readability and anti-aliasing
  * less points drawn during a great-circle route plot (only each 400NM now, was 30NM)
  * for developpers: version number and Subversion revision get set from the profile
    file QuteScoop.pro. To get the auto-updated revision right, change the version,
    check in changes to SVN, then create the release
  * for developpers: MainWindow is now called Window for consistency