Most significantly: Many thanks to JRHelbert for fixing the PJ0 and PJ1
interrupt PCMSK1 issue on the Arduino Mega! This was a great coup, in my
humble opinion.  Mega interrupt users are indebted to you, jrhelbert.

Added PinChangeIntDebug.ino, which is a simplified PinChangeIntTest. My
had was spinning in PinChangeIntTest due to a nasty bug that I whacked,
so I wanted a simplified test file.

Updated the README file. I have been calling Chris J. Kiick
"Chris J. Klick". Ooops.

Added the gpl, for completeness.
Whoops- my last commit did not include these modified files. Here they
be:

Most significantly: Many thanks to JRHelbert for fixing the PJ0 and PJ1
interrupt PCMSK1 issue on the Arduino Mega! This was a great coup, in my
humble opinion.  Mega interrupt users are indebted to you, jrhelbert.

Changed "Klick" to "Kiick" in "Chris J. Kiick"'s name. Sorry, Chris!