Fewer mpi comms

Re-think when and how we activate communication tasks and pair tasks spanning local and foreign cells.

This should result in much fewer interaction tasks, send/recv pairs, and drifts.

See merge request !373

Make SWIFT static library a dependency of all tests

We need to rebuild those after any updates.

Fixes #329. 

See merge request !376

Made sure Gizmo hydro_part_has_no_neighbours implementation does sensible things.

Set volume, gradient matrix, cell centroid and total surface area (used for flux limiter) to safe values in `hydro_part_has_no_neighbours`.

See merge request !372

Add checks for particles that are at same position and updates to the h_max of top-level cells.

Investigating #324 has turned up a couple of issues that we probably should
handle better. The first is particles with the same position. These are not 
allowed. The second is a mismatch between the cells h_max values and those
of the particles when running the ghost tasks for the first time and when
the initial estimates of h are small, so we get too many top-level cells 
initially and a regrid is needed (if this isn't done then the particles
test to be moved outside their cell and we need to rebuild, even though
a rebuild has just been done).

This fixes both by reporting an error when particles are found in the
same location, and updates the top-level cells h_max to those of the
particles (note this must be followed by a regrid as any sub-cells
will have the wrong h_max).

Also now reports if gparts are at the same location. That is inefficient
not a show stopper.

See merge request !370

We allow gparts to share locations as that will work, unlike parts (but these may as well be merged, unless they are stars)

Also reduce the verbosity of the reports

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

Fixes #326.

See merge request !371

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

Revert "Add checks for particles that are at same position, this isn't allowed, and update the cell h_max to that of the particles after the initial ghost tasks have ran. This is needed before regridding if the h values of the particles in the IC are set to be smaller than reality (ends up looking like rebuilding failed as the particles are too far outside their cells)."

This reverts commit 3d12f382.

Add checks for particles that are at same position, this isn't allowed, and update the cell h_max to that of the particles after the initial ghost tasks have ran. This is needed before regridding if the h values of the particles in the IC are set to be smaller than reality (ends up looking like rebuilding failed as the particles are too far outside their cells).

Add checks for particles that are at same position, this isn't allowed, and update the cell h_max to that of the particles after the initial ghost tasks have ran. This is needed before regridding if the h values of the particles in the IC are set to be smaller than reality (ends up looking like rebuilding failed as the particles are too far outside their cells).

Use the basename for the HDF5 files

These are relative to the container file and could include directory information (we assume XMF file is written into same directory as the snapshots).

Fixes #325.

See merge request !369

Use the basename for the HDF5 files as these are relative to the container file and could include directory information (we assume XMF file is written into same directory as the snapshots).

Subsize

Use separate parameters to determine when a pair or self interaction should be made a sub-cell task.

See merge request !365