Add periodical reset for light off

Add periodical reset for light off to avoid a light off just after
printing but after period defined, and because printing from repetier
make the flag MENU_MODE_PRINTING changing often as linked to extrusion
not acivity if no extrusion just when check lights may be set to off
when they should keep on, for SD card the flag is continuous so no
issue, so reset adding some pad allow to overlap the next checking and
avoid possibility of dead time