Avoid unneccessary +1−1 calculations
Avoid unneccessary +1−1 calculations

Move the +1 in `min(…+1, …+1, …)` out of the `min()` call,
both in the “raw C++” and in the SIMD versions.
This simplifies the code and yields a bit of a speedup.

addaleax/levenshtein-sse