Download the directory "smoother" and move it into the "libraries" directory inside your sketchbook directory, then restart the Arduino IDE. You will then see it listed under File->Sketch->smoother.

When you need more inputs/outputs for your Arduino project, the response in some forums is "Use a MEGA" instead. While the Arduino MEGA does have more built-in GPIO pins (70 digital input/output pins, ...

You’ll need additional modules (~$200 each) for digital and analog IO. On the other side, Raspi, Arduino and other toys have some IO onboard. But (I hope :) no one will ever use them for ...