Add utility methods to SparseCostMatrix.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Rename and finalize the SparseLinker.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Embryonic sparse LAP tracker integrated into TrackMate.

Does not generate track - BUG.
Just meant to do the frame to frame tracking.
Signed-off-byy Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>