Revert much of last commit, need to unskip tasks of progeny as well, note this means that we cannot just skip non-local cells, we just contract to not actually drift those

All active cells must be drifted so do not skip them if rebuilding.

If rebuilding no need to unskip tasks, that will be after the rebuild

Make sure we visit all related sends of the tasks, not just of the cell

Merge branch 'mark_tasks_in_drift' of gitlab.cosma.dur.ac.uk:swift/swiftsim into mark_tasks_in_drift

This reverts commit d5191f16.

Print hostname

Prints the name of the host at runtime for each MPI rank when the verbosity level is set to 2 and the name of the host by default when MPI is not activated.

See merge request !263

Moved the un-skipping of tasks to a separate function. Abort drifting when forcerbuild is on. Access forcerebuild atomically.

Add debugging checks to make sure all the active tasks are scheduled and that no inactive task is being run.