Pydub

- Fix `pydub.utils.mediainfo_json()` to work with newer, backwards-incompatible versions of ffprobe/avprobe

- Adds support for audio with frame rates (sample rates) of 48k and higher (requires scipy) (PR 262, fixes 134, 237, 209)
- Adds support for PEP 519 File Path protocol (PR 252)
- Fixes a few places where handles to temporary files are kept open (PR 280)
- Add the license file to the python package to aid other packaging projects (PR 279, fixes 274)
- Big fix for `pydub.silence.detect_silence()` (PR 263)

- NOTE: Semi-counterintuitive change: using the a stride when slicing AudioSegment instances (for example, `sound[::5000]`) will return chunks of 5000ms (not 1ms chunks every 5000ms) (222)
- Debug output from ffmpeg/avlib is no longer printed to the console unless you set up logging (see README for how to set up logging for your converter) (223)
- All pydub exceptions are now subclasses of `pydub.exceptions.PydubException` (PR 244)
- The utilities in `pydub.silence` now accept a `seek_step`argument which can optionally be passed to improve the performance of silence detection (211)
- Fix to `pydub.silence` utilities which allow you to detect perfect silence (233)
- Fix a bug where threaded code screws up your terminal session due to ffmpeg inheriting the stdin from the parent process. (231)
- Fix a bug where a crashing programs using pydub would leave behind their temporary files (206)

- Add new parameter `gain_during_overlay` to `pydub.AudioSegment.overlay` which allows users to adjust the volume of the target AudioSegment during the portion of the segment which is overlaid with the additional AudioSegment.
- `pydub.playback.play()` No longer displays the (very verbose) playback "banner" when using ffplay
- Fix a confusing error message when using invalid crossfade durations (issue 193)

- Allow codec and ffmpeg/avconv parameters to be set in the `pydub.AudioSegment.from_file()` for more control while decoding audio files
- Allow `AudioSegment` objects with more than two channels to be split using `pydub.AudioSegment().split_to_mono()`
- Add support for inverting the phase of only one channel in a multi-channel `pydub.AudioSegment` object
- Fix a bug with the latest avprobe that broke `pydub.utils.mediainfo()`
- Add tests for webm encoding/decoding

- Add a new constructor: `pydub.AudioSegment.from_mono_audiosegments()` which allows users to create a multi-channel audiosegment out of multiple mono ones.
- Refactor `pydub.AudioSegment._sync()` to support an arbitrary number of audiosegment arguments.