periodogram for kzf

• Implement a plotting routine that plots the periodogram for all target values and all stations.
• Also implement this plot for each input seperated.
• How does it look when merging all variables?
• Add possible strong signal points as vline: 1/365.25d, 1/7d, 1/3d, 1d
• create a plot that highlights the difference between distinct time series components after filter application
• use multiprocessing for acceleration?

This is just a blueprint of this plot.

Using many stations, this plot can become quite massive. Therefore think about an information reduction by using mean energy + std / pipe

• create aggregated periodogram