0.5

#222: added int cast for inferred length in sonify.clicks
#225: improved t-measures and l-measures
#227: added marginal flag to segment.nce
#234: update display to use matplotlib 2
#236: force integer division in beat.pscore
#240: fix unit tests for source separation
#242: use regexp in chord label validation
#245: add labeled interval formatter to display
#247: do not sonify negative amplitudes in time_frequency
#249: support gaps in util.interpolate_intervals
#252: add modulo and length arguments to chord.scale_degree_to_bitmap
#254: fix bss_eval_images single-frame fallback documentation
#255: fix crackle in sonify.time_frequency
#258: make util.match_events faster
#259: run pep8 check after nosetests
#263: add measures for chord over- and under-segmentation
#266: add amplitude parameter to sonify.pitch_contour
#268: update display tests to support mpl2.1
#277: update requirements and fix deprecations
#279: isolate matplotlib side effects
#282: remove evaluator scripts
#283: add transcription eval with velocity