Shut some warnings.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
JUnit tests for IDSet.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Add JUnit as a Maven dependency.

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

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Javadocs for IDSet.

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