Port Showfoto thumb-bar to Qt4 model/view
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ThumbBarView is a Qt3Support class based on Q3ScrollView class which will disapear with next Qt5.
This class still only used by Showfoto editor. It must be ported to Qt4 model/view implementation 
using already existing common classes used in digiKam core.

These common classes are based internally to ImageInfo container to play with item data. Showfoto do not use digiKam Database, so
we cannot use these common classes as well in Showfoto.

Common classes used to define Model/View digiKam thumb-bar are listed below by order :

DigikamKCategorizedView : initialy taken from KDELibs (KCategorizedView - used by Dolphin for ex.), 
                          this class is a bug-fix:adpated model/view core implementation based on QListView to display an icon-view.
                          This class do not depand of digiKam DB.

DCategorizedView        : it's a derivated class from DigikamKCategorizedView, with add D&D support through DragDropViewImplementation
                          This class do not depand of digiKam DB. It's add too tooltip support.

ImageCategorizedView    : a DCategorizedView re-implementation using digiKam DB. It's lead digiKAm icon-view implementaion.

ImageThumbnailBar       : ImageCategorizedView re-implementaion as a simple line thumb bar

Showfoto use KUrl to identify item, and extract data relevant (as Exif metadata for ex, through DMetadata).
To port Showfoto thumb-bar to model-view, a new class must be derivated from DCategorizedView using KUrl as lead item info.
Some methods from ImageCategorizedView and ImageThumbnailBar must be backported to play with KUrl, instead ImageInfo.

You can take a look at work done this summer about Import ported to model/view, especially on classes ImportCategorizedView 
and ImportThumbnailBar, which do not depand of digiKam DB and use CamItemInfo container.
