SONCreateFile

  SONCREATEFILE creates a new SON file
      FH=SONCREATEFILE(FILNAME, NCHANS, EXTRA)
          FILENAME = string wiht file and path
          NCHAN = number of channels 32 to 256
          EXTRA = number of bytes to reserve for user specified data
              area in the file header.
  Returns FH, a file handle or a negative error code

  This function replaces SONOpenNewFile
  See also SONOPENNEWFILE

  Author:Malcolm Lidierth
  Matlab SON library:
  Copyright © The Author & King's College London 2005-2006