Remove debugging output, tidy up output and make sure we return restart files in order, at least up to 1M files.

Make restart files dump after a number of hours from the start and synchronize dumps across MPI ranks

Needed to save and restore the current partition

Don't have any cells yet

Update the total number of particles in the run after the replication process.

See merge request !490

Moved restart_write into engine_step and trigger after drift_all

Tidies up the restart option

Unify the first initialisation of the part and xpart arrays. Correctly set the ti_drift and ti_kick for gparts and sparts.

Better function name for the first initialiation of all the parts at the very start of engine_init_particles()

Add chemistry in part

See merge request !486

Start reorganizing so we can restart, doesn't work yet

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.

Add a function that returns the name of a specific chemistry element. Use that function to print the names in the snapshot header.

Make the enum containing the various chemical species a common feature accross all chemistry models. Fixed typo and documentation.