More consistent object id handling

- parse id and targetId attributes of KML objects
- write id and targetId attributes of KML objects
- reuse GeoDataObject::id instead of using schemaId and styleId
SVN_SILENT made messages (.desktop file)
Add AppData for Marble.

Add AppStream meta data: http://techbase.kde.org/MetaInfo

REVIEW: 118832
SVN_SILENT made messages (after extraction)
SVN_SILENT made messages (after extraction)
Accept Placemarks as children of GeoDataChange
BUG: 336424
REVIEW: 118943
SVN_SILENT made messages (after extraction)
Added 'Merging Nodes' feature to polygons editing
REVIEW: 118885
SVN_SILENT made messages (after extraction)
SVN_SILENT made messages (.desktop file)
Reduce to 3 landings for now; add balloon popups for each.
Also control zoom during camera interpolation
make plugin work again
Use the widget's lookAt directly, not the focusPoint
Fix memory leak
Use the widget's lookAt instead of the focusPoint, set altitude
Make sure to hit the target
Fix interpolation of the very first/last fly to
Open/Close placemark balloons during tour playback
BUG: 336434
REVIEW: 119003
SVN_SILENT made messages (after extraction)