Add functionality to help prevent OLED burn in/dimming

[JeffCurless]

if ENABLED:

Display screens as usual
At a specified time, blank the screen and stop future displays
When the user presses the button, start a screen rotation again… and start the process all over again.

If NOT ENABLED (i.e. how it actually works today)

Display screens as usual
if the screen saver time is less than the display time, blank at screen saver
once screen display time is up, display new screen (awaking up screen if needed).