Currently if a file is selected the dicom image reader will always look at all dicom files in the directory and trys to load them as images.

If a file is selected only the image block containing the file should be loaded. No matter what other image blocks where find in the directory.

As a side effect, this also corrects the strange behavior that it can happen that one selectes a series in the DICOM editor but several series are loaded (because they are in the same directory :P).