add  missing value checks for the columns: "original labeling" and "labeling"
Bug fix in WaehlbySplitter: Transitive dependencies not resolved

When setting a high distance merge threshold, already merged objects
may be merged again, but with a different label. Therefore their actual
label is not present anymore in the labeling but still in the list of
merged labels. This leads to a NullPointerException.
WaehlBySplitterOp: Minor code cleanup
Converter: Use converter to wrap image
Merge pull request #80 from knime-ip/waehlby_fixes

Fixes transitive dependency bug of already merged labels
Merge pull request #77 from knime-ip/trackmate-fixes

Trackmate add more missing value checks
SegmentFeatures: only "virtually" create binary mask
SegmentCropper: Only virtually create cropped segment if applicable
Merge pull request #82 from knime-ip/segment-cropper-improvements

Segment cropper improvements
fix import in TrackmateTrackerNodeModel
Replaces Imgwriter with a scifio-based reimplentation.
- more options in the node settings
- various bugfixes
Renames new ImgWriter to Image Writer 2, reintroduces deprecated ImgWriter for backwards compatibility
Dialog and node description improvements