If the neighbour count goes above NUM_OF_NEIGHBOURS don't log the neighbour id but keep logging the neighbour count.

Use intrinsics for vector operations as arithmetic overloading is not supported by the Intel compiler yet for AVX-512 vectors.

Conflicts:
	src/hydro/Gadget2/hydro_iact.h

Use intrinsics for vector operations as arithmetic overloading is not supported by the Intel compiler yet for AVX-512 vectors.

Conflicts:
	src/hydro/Gadget2/hydro_iact.h

Use intrinsics for vector operations as arithmetic overloading is not supported by the Intel compiler yet for AVX-512 vectors.

Updated the way we converge towards the smoothing length. We now use a Newton-Raphson scheme. This applies to the Gadget-2 scheme.

Created a vectorised version of runner_dopair2_force that computes the interaction and masks at the same time as the neighbour search.

Removed un-masked versions of the force interaction and incorporated them in runner_nonsym_force_2_vec with an if statement based on a hard coded mask_cond variable.

Created a typedef for a mask object to abstract the mask creation away from the user and placed it in vector.h.