Don't read h into cache when calculating subset density interactions as h is not used in the function and causes a race condition warning in the thread sanitizer.

In the vectorized cache construction, return 0 and an error message when not compiling with GADGET2-SPH.

Better choice for the padded smoothing lengths when constructing hydro caches. We can't use the 0th particle as it might be inhibited (and hence garbage) and we can't just use a constant.

In runner_doself1_density_vec(), construct the padded positions only once for all the particles instead of once per 'i'.

Place inhibited particles out of range of neighbouring particles so no interactions are computed. cache_read_particles_subset().

Subpair density vectorised now runs fine with Sedov Blast and EAGLE_6 examples with sorted interactions.

Make sure the code compiles with vectorization switched on and using a different hydro scheme from Gadget-2.