[calib2] Rework fitting as job processing

[vallsv]

Allow to compute asynchronously, and to store history of each fits.

This should thread the computation of the class RingCalibration. Ideally it should be done as new jobs, everytime the geometry is updated.

The class RingExtractorThread could be used as a reference.

[kif]

use a processing queue to update

• fit of the geometry
• marching-squares to update rings (...)