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

Conflicts:
	src/cache.h
	src/runner_doiact_vec.c

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

Don't need to load unneeded quantities until they are actually left-packed into the interaction cache.

Disable particle cache when vectorisation is disabled.



See merge request !337

Quicker to find neighbours with only 1 vector and no need to mask result of interaction if the remainder interactions have already been performed.

Created a horizontal maximum with intrinsics, which turns out to be slower than a simple for loop over the vector in AVX at least.

Pass vectors by address instead of value and use 2 vectors to find neighbours in runner_doself2_force_2.