FIX: In first_start_of_match, remove unneeded alignment code
FIX: In first_start_of_match, remove unneeded alignment code

We don't need to treat the unaligned part separately. Rename the methods
to reflect this (use _mask and _nomask). Looks like a small improvement
on benchmarks on average (a few regressions) and a big gain on the
short_short benchmark.

bluss/scratchspace,bluss/scratchspace