Add an efficient option to show thumbnails of images in the data storage inspectors.
On idea would be to put it in a QViewDecorator (alternatively in the QmitkAbstractDataStorageModel) for the DecorationRole. The decorator can use the QmitkDataNodeRole to get the data and generate a thumbnail. The thumbnails should be cached (e.g. in a map keyed by the data UID) to avoid unncessary regeneration of thumbnails (or as a alternative stored as a property of the node?).
I would propose that as default the thumbnail should allways be the middle z slice of the image cube.