Fix bug that was showing multiple objects even if the original segmentator used a single one.

Bug pointed out by Annet Jannasch. The problem was the call to the method to keep only large components was commented because it would fail in case no initial foreground pixels were provided. Now, it is only called if there are predefined foreground pixels. It there are not, a new method is called to preserve only the largest of all components.
Add class to test and debug GUI
Update Fiji-pom version to developing one.

Otherwise, some debug classes are not found.