Scaper

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- Source separation support! Add option to save isolated foreground events and background audio files.
- Makes pysoundfile a formal dependency.
- Seeding tests more robust.

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- Added a random_state parameter to Scaper object, which allows all runs to be perfectly reproducible given the same audio and the same random seed.
- Switched from numpydoc to napoleon for generating the documentation. Also switched Sphinx to the most recent version.
- Added functions to Scaper object that allow one to reset the foreground and background event specifications independently. This allows users to reuse the same Scaper object and generate multiple soundscapes.
- Added a function to Scaper that allows the user to set the random state after creation.

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- Added functionality which modifies a source_time distribution tuple according to the duration of the source and the duration of the event.
- This release alters behavior of Scaper compared to earlier versions.

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- Fix bug where temp files might not be closed if an error is raised

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- Store sample rate in output JAMS inside the scaper sandbox

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- Fix bug where estimated duration of time stretched event is different to actual duration leading to incorrect silence padding and sometimes incorrect soundscape duration (in audio samples).