A suggestion to remove confusion regarding periodograms

[goznalo-git]

Hi there,
I've been recently reading about this Python library, because I needed to plot some periodograms. And it has proven to be a very frustrating experience. At first glance it seemed that WelchPeriodogram was a class, just like Periodogram itself. The same goes for DaniellPeriodogram. That caused me quite a lot of confusion until I read the souce code. And at least DaniellPeriodogram does have a class one can call, pdaniell, why not WelchPeriodogram? What am I missing?

Thank you for your effort though!

[cokelaer]

@goznalo-git sorry for the confusion, I have developed spectrum a long time ago and my choice at that may not have been the best. The OOP was definitely a good choice but the user interface not. Since it is usde by quite a lot of users, I will probably keep it it this way for now for all back compatibities. I'll be happy to discuss more about it tough