0.4

#189: expanded transcription metrics
#195: added pitch contour sonification
#196: added the display submodule
#203: support unsorted segment intervals
#205: correction in documentation for sonify.time_frequency
#208: refactored file/buffer loading
#210: added io.load_tempo
#212: added frame-wise blind-source separation evaluation
#218: speed up melody.resample_melody_series when times are equivalent