Tiny Filament Sensor - Optical Version using Tiny Photoelectric Sensor

/**

• Filament Runout Sensors
• Mechanical or opto endstops are used to check for the presence of filament.
• RAMPS-based boards use SERVO3_PIN for the first runout sensor.
• For other boards you may need to define FIL_RUNOUT_PIN, FIL_RUNOUT2_PIN, etc.
• By default the firmware assumes HIGH=FILAMENT PRESENT. */ //#define FILAMENT_RUNOUT_SENSOR