Non-binary fractional circular primitives

[Travis Cobbs]

Or we could just add the following text (or similar) to the Primitives Reference:

To avoid rounding errors, it is preferable to use existing (or create new) fractional circular primitives rather than rotate an existing primitive by anything other than 90 degrees. For example 3-16XXXX.dat is preferred to combining 1-8XXXX.dat with 1-16XXXX.dat rotated by 22.5 degrees.

I like this option.