improvement
- Automate release #228
- demuxer : refactor interface to prepare for mp2ts container support
- support start fragment prefetching in case media not attached yet (disabled by default)
- abr-controller: don't update bw metrics if fragment has already been loaded
bugfixes
- streamController: fix recoverMediaError() not reseeking to last media.currentTime
- SPS Parser : ensure width is an integer #252
- bufferController : fix "TypeError: this.config is undefined" #248
- NPM : export dist, and change main to './lib/hls.js'