API name `(i)qct/(i)qst`, easy-to-read help document?

[zoziha]

Problem 1: The API name (i)qct?

I improved the interfaces and its documentation of dcosq routines in this branch (I may consider submitting a PR tomorrow?). They compute the fast fourier transform of quarter wave data, but I don't know enough about them ("quarter wave data"), this involves more professional terms and I can't even find their corresponding routines in scipy.fftpack.
What should their simplified modern interface be called? qct(Quarter-Cosine Transform)?
(see https://www2.cisl.ucar.edu/resources/legacy/fft5/documentation)

Problem 2: more complex document (fftpack.md) that is difficult to read for users?

fftpack.md is getting more complicated and may be difficult to read?
It contains original fftpack routines (dfft/dzfft/...), modern interfaces (fft/rfft/...), and utility functions (fftshift).

Maybe we can divide the existing fftpack.md into three markdown documents: fftpack_classic_API.md, fftpack_modern_API.md, fftpack_utilities.md.

This issue is not urgent, I am just worried.