more tags

• add support for multiple bitrates #4
• translate relative path to absolute #5
• support for #EXT-X-CUE-OUT-CONT tags as attributes of Segment
• support for #EXT-X-INDEPENDENT-SEGMENTS
• add strict mode
• added AVERAGE-BANDWIDTH
• lots of bug-fixes and minor improvements

THANKS A LOT @Neon-Dlea , @mvmocanu , @GrumpyOldTroll , @cristina0botez and many others 👏