SONCreateChannel

  Obsolete function. To write to a file use the SON32 library

  Create a new channel in  SON file fid using the existing channel SrcChan channel header as a template.
  Channel data is contained in data. If data is type int16 a new ADC channel will be written. If floating point a 
  RealWave channel will be written as long as the file is of a high enough version (6 or beyond)
  Returns the SON channel number of the created channel

  Malcolm Lidierth 02/02

  14/5/03 Add feature to use title  from input dataheader for new channels comment
  21/5/03 If writing ADC data update the units field in the channel header