some have many keys one for each item.
bind a new DataModel into QML that will be associated to a specific DataSource and a key pattern
an exact one like "items" of rss
or a partial regexp one like "KnowledgeBase-[\d]*" like the ocs engine
in this way is not necessary to change how those dataengine works and is possible to use them in QML without headaches
svn path=/trunk/KDE/kdebase/runtime/; revision=1189953
