Updated the 20 MHz side of the code to only work with the high-speed protocol (copied from pololu-led-strip-avr repository).
Updated the 16 MHz side to work with the high-speed protocol.  It as not as fast as it could theoretically be; it takes about 1.1 ms to update 30 LEDs.
Removed some un-needed ifdefs.
Updated the version to 2.0.0 and updated the README.