Open only once dependency file and add an option in debugging-checks mode for writing task dependency graph

Large hdf5 reads

See merge request !453

When compiling with the iosthermal equation of state, read the constant thermal energy from the YAML file.

Resolve "Check for drifted state in vectorized tasks"

Closes #380

See merge request !449

Doself subset vec

See merge request !445

List top-level cells with tasks

See merge request !441

Fix pair vec exit iteration

See merge request !447

Fix spelling

See merge request !448

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

Bug fix: Fix the exit iteration padding.
 - Removes padding for the exit_iteration when looping over cj.
 - Calculates the padding correctly for the exit_iteration when looping over ci

See merge request !446

This reverts commit ab51e592.