New Arduino Keyboard Library can Read 6 Buttons using only 3 I/O pins

I've written a new key input library that supports a special type of multiplexing that can scan 6 buttons using only 3 I/O pins, 10 buttons using 4 I/O pins, 15 buttons using 5 I/O pins, and so on. For more details, see my web page and video at:

Introducing KeyPlexLib (or, 'Wayneplexing' on Arduino Made Easy)