v0.8.68

The screen-off of 0.8.67 was abrupt; asked for gradual.

• The screen goes black and comes back over a fade. "Over, milliseconds" beside "Screen off after" in the look panel: how long the screen takes to go black and to come back, 500 (half a second) unless said, 0 for at once, up to 120000 (two minutes). The face's setting face.idle.fade, in a face theme [idle] fade. Drawn by glass-evo from 0.1.36.