Add the toggle link action.

Assigned by default to the L key.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
A track analyzer that returns cell division rate.

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

And enforce recalculation of features according to the providers even
upon loading an existing file. This is done so as to benefitiate from
new feature analyzers even on an existing annotation.

Signed-off-by: Jean-Yves Tinevez <jean-yves.tinevez@pasteur.fr>
Exploits the spot coloring per track feature.

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