Extractor code and output should be consistent with MusicExtractor

[dbogdanov]

The code for the Extractor algorithm is outdated compared to our recent updates of the MusicExtractor algorithm. We should ensure that both algorithms are consistent in their code and produced output. Ideally, both algorithms should share the same code base. The difference between them would be in that Extractor requires audio as an input while MusicExtractor works with files.