prtOutlierRemovalNStd  Removes outliers from a prtDataSet
 
    NSTDOUT = prtOutlierRemovalNStd creates a pre-processing
    object that flags as outliers data where any of the feature values is
    more then nStd standard deviations from the mean of that feature.
  
    prtOutlierRemovalNStd has the following properties:
 
        nStd - The number of standard deviations at which to flag an
               observation as an outlier an observation (default = 3)
 
    A prtOutlierRemovalNStd object also inherits all properties and
    functions from the prtOutlierRemoval class.  For more information
    on how to control the behaviour of outlier removal objects, see the
    help for prtOutlierRemoval.
 
    Example:
 
    dataSet = prtDataGenUnimodal;               % Load a data Set
    outlier = prtDataSetClass([-10 -10],1);     % Create and insert
    dataSet = catObservations(dataSet,outlier); % an outlier
 
    % Create the prtOutlierRemoval object
    nStdRemove = prtOutlierRemovalNStd('runMode','removeObservation');
 
    nStdRemove = nStdRemove.train(dataSet);    % Train and run    
    dataSetNew = nStdRemove.run(dataSet);  
  
    % Plot the results
    subplot(2,1,1); plot(dataSet);
    title('Original Data');
    subplot(2,1,2); plot(dataSetNew);
    title('NstdOutlierRemove Data');