0.10.0b4

Better

• Uses much less memory: memory an AI model needed for one image is now given back after
  each check instead of being held for the rest of the run, and the state classifier no longer
  loads scikit-learn. On a test installation with nine sensors and face recognition the app went
  from about 940 MB to about 580 MB. A check takes a few percent longer.
• State sensors are retrained once after the update, from their stored training images (it takes
  a moment, and the sensors keep their last state meanwhile).