[Bug] FlowPlayer skips Opus-encoded audio tracks when gap-less playback is enabled

[Olf0]

For details see #67 (comment).

Note that:

• This does not seem to affect other codecs: FLAC and MP3 are tested.
• Without enabling gap-less playback in FlowPlayer's settings Opus-encoded audio files with multiple tracks play fine: No tracks are skipped.
• This is most likely not FlowPlayer's fault.