Redondant call to PyWorld

[ghost]

in utils.py - line 262
redondant call to wav2world
>>> feats=pw.wav2world(vocals,fs,frame_period=5.80498866)
removing this line allow to speed up the precomputing prep_data_nus.

EDIT:
Wrong assertion (feats is used before recall), sorry. But maybe the code can be adapted to just copy feats to ap & harm and not recall pw.wav2world that is computational intensive (and called 96 x 2 in the NUS database case).