Add the possibility to read basic chemistry information from the parameter file and propagate this onto the particle at initialisation time. More uniform naming convention for the first initialisation of properties.

Grackle chemistry --> GEAR chemistry. Moved the output of subgrid model to a separate part of the HDF5 file.

This reverts commit d6acb7a1.

Meant to add to another branch...

Make use of a temporary threadpool in the reading routines to speed-up the duplication of parts into gparts.

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

Add information to stdout and timestep.txt about what happened in the step (rebuild, repartition, snapshot, ...)

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

There is a problem when the cpu mask is empty and using multiple MPI ranks on a node, in that case all the main threads end up pinned to one core during the reading of the initial condition (and any other tasks done before engine_init is called).

Compute one octant of the Ewald corrections at start-up for future use when running with the gravity checks.

This reverts merge request !375