Spectrum class - Work in Progress

The spectrum class contains besides the spectral values also information
about the frequency bands and should allow easy conversion from
narrowband to fractional-octave band and from higher fractions to lower
fractional-octaves.


While I think such a class can be very useful it also seems like adding too much overhead.
Just having a class describing the spectrum, with the spectral values/data separated might be better. What do you think?