A working sparse tracker, needs some polishing.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Utility classes and methods for sparse cost matrices.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Spot is now Comparable.

Based on its unique ID. Has application for qui retrieval in sorted
lists.
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Big rework of the design of the sparse LAP packages.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Simplify JaqamanSegmentCostMatrixCreator.

Reuse components!
Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>