Compare different SIMD tiling methods

- A*PA2: diagonal tiling of SIMD lanes
- SeqMatcher: using SIMD as a u256 / u512, see here for some nice algos: http://www.numberworld.org/y-cruncher/internals/addition.html#ks_add
- What's currently in sassy: aligning 4 chunks of the text in parallel, so that lanes are independent.