Why replace seqNo 0 to 1?

I think `#EXT-X-MEDIA-SEQUENCE` value is allowed `0` (example: [Technical Note TN2288: Example Playlist Files for use with HTTP Live Streaming](https://developer.apple.com/library/ios/technotes/tn2288/_index.html#//apple_ref/doc/uid/DTS40012238-CH1-TNTAG2)), but `0` is replaced now. Why?

[m3u8/writer.go at master · grafov/m3u8](https://github.com/grafov/m3u8/blob/master/writer.go#L313-L315)
