Updated the 20MHz side of this code so that it only works with the new high-speed strips.  I still need to update the 16 MHz side, but I also updated the documentation.
Updated led_strip2.c to use the faster protocol.
Removed led_strip3.c because it is not easy to update it to the high-speed protocol.  However, I would like to dig it out of git some time and see if I can get it to work somehow.
Updated the 16 MHz side of the code to work with the high-speed protocol (copied it from the pololu-led-strip-arduino library).