A set of overlapping activities

[YOUSSEF HOUIET]

This new constraint would allow a defined set of activities to overlap in time (partially or fully).

Possible use cases include:

-Two or more teachers working at the same time.
-Two or more student groups scheduled at the same time whenever possible (for example, to ensure they can share the same school transport in rural areas).
-Synchronizing multiple sub-activities in pairs (such as English and Spanish lessons running in parallel).

This constraint is related to the existing "A set of activities occupies max selected time slots", but it would be more practical to have a dedicated one for overlapping activities.

If it is easy to implement, the new constraint would be very useful. Otherwise, the existing constraint can still be used as an alternative.

[Liviu Lalescu]

Thank you, Youssef! It is not very complicated to add, but I prefer to use the existing constraint.