Adding a screen saver

[mrosseel]

• added new config option 'Screen Off'
• When the unit is idle for this amount of time, the screen is turned off, preventing burn-in and lowering power consumption.
• when pressing a key to get out of screen off/lower brightness mode, the key is now properly ignored
• wake on motion also works for the new screen off mode

See the .hide() method in the docs below: https://luma-oled.readthedocs.io/en/latest/api-documentation.html#module-luma.oled.device

[mrosseel]

@brickbots

• for screen dimming the Off setting is 100000 secs or 27 hours. Is this a feature or can I replace this with -1 and handle it in code to really mean Off ? That's how I did it now let me know if I should revert it. I wouldn't mind a failsafe where the screen turns off after a few hours, but not sure about it.

• what's the min/max for the keypad brightness? Would want to keep the keys on when the screen is off so the unit doesn't look dead. Of course if keypad brightness is set to 0 that could be honored. Would just be good to know the limits and split off the keypad brightness so I can set it seperately.

[brickbots]

The 100000 seconds was just to have some value to avoid checking for the 'off' condition. Your implementation is much more legible and future proof 👍

The min/max for the keypad PWM is 0/100. Basically the percent of the duty cycle the output is high.