Bugfix for MP4Demuxer

• improve code effiency
• fix files without ctts
• fix xhr withCredentials
• a lot probable audio sync fix

Several fixes for MP4Demuxer

• timescale pass to MP4Remuxer as original (no longer fixed to 1000)
• Support files bigger than 2 GB (co64 box and big mdat box support)
• Pass accurate duration calculated by moov data back to transmuxer controller and update segment timestampBase
• Drop extra data after chunks

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• 时间度量按照原样传递给MP4Remuxer（不再固定为1000）
• 支持大于2GB的文件（支持co64和大的mdat）
• 将moov计算得出的精确时长传回转封装控制器并更新分段时间基数
• 丢弃区块后多余数据

Dec 14, 2017

• Added fix for files no ctts given
• 修复无ctts文件出错

Fix incorrect keyframesIndex

What's new in this build

• Fix incorrect keyframesIndex
• Added es6 bundled version
• Added a video desync fix

Merge v1.3.0 from mainline

Original release note

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Jun 10:
included f132248

Fix bug where every video sample has same cts

这个bug并没有在firefox下造成任何播放问题，但是chrome会受到严重影响，具体表现为画面抽搐。

This bug didn't cause any playback problem in firefox since I was always testing in firefox. But chrome will be affected badly by this bug, which the video will become laggy.

Segment MP4 playback

添加了一个MP4解封装器以支持分段mp4播放。
*不支持moov box在尾部的文件

同时含有flv播放的实时码率计算。

Added an MP4 demuxer to support segment MP4 playback.
*Does not support file with moov box at the end.

Also flv playback with realtime bitrate calculation added.