BTW, I am still testing this release but I wanted it to get out there because I uncovered some nasty bugs. They made my interrupts unreliable! So it's important if you use this code, to realize that the new version should work better.
I realized that about 5-10% of my interrupts were missed due to my switch bounce; some of the bounces happen only 50 microseconds apart or so. And my code was not processing them properly. With this code, I notice that my switches are more reliable.
I also notice that I am not getting the speed bump that I hoped to get, and some of my bugfixes actually introduce a few extra microseconds of processing. This is disappointing and I hope to find them if I can.