Merge remote-tracking branch 'tjoppen/opatom_demuxing_and_seeking'

* tjoppen/opatom_demuxing_and_seeking:
  mxfdec: Index table driven demuxing and seeking
  mxfdec: Compute packet offsets properly
  mxfdec: Use MaterialPackage - Track - TrackID instead of the system_item hack
  mxfdec: Parse more values in PartitionPack
  mxfdec: Parse TemporalOffsets
  mxfdec: av_dlog():ify 'no corresponding source package found'
  mxfdec: Compute essence container offsets and lengths into mxf->partitions
  mxfdec: Make mxf->partitions sorted by offset
  mxfdec: Parse ThisPartition
  mxfdec: Speed up metadata and index parsing
  mxfdec: Make sure DataDefinition is consistent between material track and source track
  mxfdec: Add EssenceContainer UL found in 0001GL00.MXF.A1.mxf_opatom.mxf

Merged-by: Michael Niedermayer <michaelni@gmx.at>