SONGetBlockHeaders

  SONGETBLOCKHEADERS returns a matrix containing the SON data block headers
  in file 'fid' for channel 'chan'.
  The returned header in memory contains, for each disk block,
  a column with rows 1-5 representing:
                        Offset to start of block in file
                        Start time in clock ticks
                        End time in clock ticks
                        Chan number
                        Items
  See CED documentation for details - note this header is a modified form of
  the disk header

  Malcolm Lidierth 02/02
  Updated 06/05 ML
  Copyright © The Author & King's College London 2002-2006