code refactor and library modules version update

[NullXeronier]

@liuhaumin How to experiment this project now?

conda create env failed.

• midi2audio==0.1.1
• imageio==2.1.2
• mido==1.2.8
• pretty-midi==0.2.8
• pypianoroll==0.1.3
• madmom==0.16.dev0
• music21==5.1.0
• sharedarray==2.0.4
• markdown==2.2.0

• tensorflow-gpu==1.2.0

  please upgrade library module version

[NullXeronier]

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