gitignore: add udunits library to ignore list
TrackMate: cease use of deprecated calibration API
Update to pom-scijava 1.87

This updates the pinned Bio-Formats version to 4.4.9.
Stitching_: remove no-longer-needed SLF4J deps

These dependencies were necessary prior with the Bio-Formats 4.4.8
release, because that release used an old version of SLF4J that required
an associated SLF4J binding at runtime.

Now that Bio-Formats 4.4.9 has been released, we no longer need to
hardcode an SLF4J binding at runtime; if no binding is present, SLF4J
will simply not log anything rather than throwing an exception.