v0.19.0

• 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