Previously a for loop with two iterations was used to calculate the
3D segment locations for the input number and the higher power of 2.
Splitting off the inside of the for loop to a separate function makes
the code more readable.
This commit also includes a simple timer for bevel, enabled with a
define. Interestingly, the cleanup in this commit happended to give
a 3% speedup on a Ryzen 3700x for a bevel calculation with 64
segments.