[Pig Wiki] Update of "PigStreamingFunctionalSpec" by Arun C Murthy

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The following page has been changed by Arun C Murthy:
http://wiki.apache.org/pig/PigStreamingFunctionalSpec

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  B = stream A by `stream.pl`
  }}}
  
+ Note: !BinaryStorage *needs* the `split by 'file'` option to be specified, 
else it isn't guaranteed to work.
+ 
  ==== 4.4 Working with scalars ====
  
  Several users need to have a way to compute a scalar using pig and use it in 
later computations.