Yowl 1.0.2

It notices a theft about ten times faster.

Reported as taking a few seconds to register a grab. The detector was never the
slow part — measured at 320×240 it costs 10.3ms a frame, enough for ~97 fps. The
delay was policy:

• Frames arrived at 5 fps, and firing wanted three consecutive hits.
• Three frames at 5 fps is 600ms at best, and a real grab is jerky — one frame
  dipping below the threshold reset the count to zero and the wait started over.

Now firing wants three hits within the last five frames, at 15 fps. A
single dip no longer throws the evidence away, while hits spread thinly still do
not fire — so a busy café cannot accumulate its way into an alarm.

Detection now lands around 200–330ms.

Costs about a seventh of one core while armed, which is less than holding the
camera open costs in the first place.

279 tests pass. Signed and notarised, universal.