The Neopixel version was not working. I updated to the latest FastLED
library that uses the RMT feature and a second core. I also updated the
code to make it easier to deal with the differences between the Neopixel
and Dotstar versions.
The Arduino IDE requires that a sketch be located in a folder of the same name. Although the name of the repository does match the sketch name, when GitHub's popular Clone or download > Download ZIP feature is used to download the contents of a repository the branch/release/commit name is appended to the folder name, causing a mismatch.
When opening a file that does not meet this sketch/folder name matching requirement the Arduino IDE presents a dialog:
The file "TWANG32.ino" needs to be inside a sketch folder named "TWANG32".
Create this folder, move the file, and continue?
After clicking "OK" the Arduino IDE currently moves only the file TWANG32.ino to the new folder, leaving behind the other source files. This causes compilation of the sketch to fail:
TWANG32-master\TWANG32\TWANG32.ino:30:23: fatal error: twang_mpu.h: No such file or directory