`get_sampling_frequency_and_duration_from_frequency_array` possibly not consistent with other utils functions

I just put this out there because I just stumbled over that. I think the utility function above might create slightly inconsistent results with create_frequency_series(sampling_frequency, duration). I am a bit too tired now to provide a concrete example (it is on my to do list for tomorrow), but I think if you try

new_frequency_array = create_frequency_series(get_sampling_frequency_and_duration_from_frequency_array(frequency_array)

the length of the frequency_array and new_frequency_array will slightly differ.