Add pyfaust.factparams.ParamsHierarchicalDFT simplified parameter structure.

Use case:

from pyfaust import dft, Faust
from pyfaust.fact import hierarchical
from pyfaust.factparams import ParamsHierarchicalDFT
import numpy as np
d = 32
p = ParamsHierarchicalDFT(int(np.log2(d)))
DFT = dft(d).toarray()
F = hierarchical(DFT, p)
print((Faust(DFT)-F).norm()/Faust(DFT).norm())

F = hierarchical(DFT, dft)
print((Faust(DFT)-F).norm()/Faust(DFT).norm())