Chebyshev Type II support

[drom]

Thank you for the awesome package.
It would be great if it could design Type II Chebyshev filters (inverse Chebyshev filters)
https://en.wikipedia.org/wiki/Chebyshev_filter#Type_II_Chebyshev_filters_(inverse_Chebyshev_filters)

[markert]

Inverse Chebychev lowpass filters can be calculated out of Type I filters by lowpass-highpass transform and mirroring. I did not implement these functions, yet. I will have a look into it.