Conflicts:
	tests/test125cells.c

These fix a bug in the range of adjacent tasks of the same type
(and colour) which meant they merged into a single bar, regardless
of whether there was a gap or not (feature of span_where).

Also update to offer proper command-line options, the main one of
which is --expand. That splits the tasks of a thread into "expand"
lines of tasks, designed so that adjacent tasks will not be on the same
line. It is now also possible to set the size of the output graphic.

The colours have also been tweaked once more.

Reset the task debugging timers every time-step

Fixes #306.

See merge request !339

Update test kernel

Removes `doself1_density_vec_2` function. Updates `testKernel.c` to include tests for `kernel_deval_1_vec` and `kernel_deval_2_vec`.

See merge request !338

Added an option to the difffloat script to ignore a certain column if the numbers are too close to 0. Used this feature for the test27perturbed column rho_dh

Disable particle cache when vectorisation is disabled.



See merge request !337

Dopair1 vectorisation merge

Summary
-------
- Contains a vectorised version of `runner_dopair1_density`
- `runners` now have two particle caches to hold cell ci and cell cj
- The `cache` has been updated to include `max_d` which is the maximum distance into the neighbouring cell
- `cache.h` contains more functions to read two cells into cache and to read a subset of particles from each cell into the cache


See merge request !320

Added softened gravity to the M2L kernels



See merge request !336

Crucial +1 for the edge case where all particles in cell ci interact with at least one particle in cell cj.

Updated runner_doself1_density_vec and runner_dopair1_density_vec to align with Pedro's recent changes in DOPAIR1 and DOSELF1.

Do not clear the sort flag when receiving parts after the ghost.

Implements #304. We only reset the c->sorted flag for the first receive not for the second one. 

See merge request !335

Do not clear the sort flag when receiving parts after the ghost. We can re-use the sort from the density.

Removed the 'tight' property of the tasks. Only density pairs need to be tight so we can just use that.

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.

Merge branch 'dopair-vectorisation-merge' of gitlab.cosma.dur.ac.uk:swift/swiftsim into dopair-vectorisation-merge

Conflicts:
	src/runner_doiact.h

Rebuild criteria

Instead of rebuilding whenever the cell constraints or sort indices are violated, just re-sort in case of the latter.

This lead to some other changes:

 * Init tasks are gone, particle initialization is now handled in the drift tasks,
 * Drift tasks no longer act on the super-cell, but exist at every level similar to the sort tasks,
 * Fixed several dependency issues with sort and drift tasks,
 * Only drift/sort on-demand in the sub-cell tasks.

Marked as [WIP] as this has not yet been tested for MPI runs, or with gravity.

See merge request !327