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

Make sure the GIZMO extra loop uses the in and out ghost tasks and not just the main ghost task. Code formatting.

This is a requirement of fopen()

Also use errno to get the detailed error about the failure

The task plot analysis scripts now also displays the number of particle updates done in that time-step. It also shows the time distribution for pairs sorted by SID.

Add -P command-line option to overwrite or add program parameters without modifying the YML file, useful for quick tests

Add a separate timer for subset sub-cell tasks. Write the timers to a file. Make sure we can compile without timers. Add a configure option to switch the timers on.

Replaced global variables by a new hydro_space struct that is part of space. This struct is then passed on to hydro_init_part, and used to initialize the Voronoi cells. For non SHADOWFAX_SPH schemes, this struct is empty. Replaced random_uniform declarations in some unit tests with the tools.h version. Added some more comments to 3D Voronoi code; it is now almost completely documented (meaning I almost completely understand it now).

cputimes output file to avoid an MPI call each step. General tidyups
to remove unneccesary values and to keep APIs clean.