Make spectral rolloff return bound values

[Polochon-street]

Hi,

The current code returns an out of bound bin (length + 1) if everything is contained in the last bin. This returns instead the last bin.

Not really sure where to test that, but here's a small excerpt that shows it working:

X = [0., 0., 0., 0., 1.]
cumsum = 0.

for x in X:
    cumsum += x

cumsum *= 0.95
j = 0
rollsum += X[j]

while rollsum < cumsum:
    j += 1
    rollsum += X[j]
print(j)

It returns 4 (the right value), and if you instead use

j = 0

while rollsum < cumsum:
    rollsum += X[j]    
    j += 1
print(j)

you can see it returns 5, one too much.

We could also do it the other way, where you go through the norm array and then break whenever you reach 95% of the energy, but I didn't want to change stuff too much :)

[Polochon-street]

Build seems to fail because of missing public keys?

[rec]

Ah, I appear to see that too: #312

See also: #317

[Polochon-street]

@rec yep, tried to rebuild it today - failed. I guess we just need to wait til the key is updated 😄