Added constructor to ScifioImgSource that allows to pass a SCIFIOConfig object (allows one set scifio-specific settings from outside)
New way to pass settings from the image reader to the ImgOpener via the SCIFIOConfig-object
Remove some lines from the previous commit that caused compilation errors.
Check if the currently read file really contains images and throw a knip-exception, if not.
Wrap the reader used in the ScifioImgSource with a UnclosableReaderFilter to prevent him from being closed.

The reason: if an image is opened via the ImgOpener the metadata is reset afterwards (even if just one series of the current image file is read). To read another series of the same file the file has to be parsed again, what might be a bit expensive for some file formats.
Now, as the reader is unclosable, it is closed not before all desired series have been read.

Conflicts:

	org.knime.knip.io/src/org/knime/knip/io/ScifioImgSource.java
Pass the scifioConfig-object at each setSource-call on the reader.