New & improved Button library

Hey all,

I made a bunch of helpful updates to the Button library: http://log.liminastudio.com/itp/physical-computing/arduino-a-new-improved-button-library-with-some-handy-features

Mainly added built-in debouncing, added lots of examples, and made the asynchronous methods a bit more helpful.

Please try it out and let me know if you find any bugs.

—t3db0t