Fix TableView delegate to work with C++ models again.

Use the views's delegate 'model' property for accessing both
Qml ListModel and C++ QAbstractItemModel values.

For Qml objects, QObject and QObjectList based models modelData
properties will be used.

For models without roles (Integer, Array, QStringList) modelData
is used directly.

A new manual test for all model types is included.

Change-Id: I9934ff9737e1b687b852f2413b2d7484248c4e6e
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>