prtDataGenBimodal   Generate bimodal example data 
 
   DATASET = prtDataGenBimodal returns a prtDataSetClass with randomly
   generated data according to the following distribution.
 
        H0: 1/2N([0 0],eye(2)) + 1/2*N([-4 -4],eye(2))
        H1: 1/2N([2 2],[1 .5; .5 1]) + 1/2*N([-2 -2],[1 .5; .5 1]
 
   Example:
 
   dataSet = prtDataGenBimodal;
   plot(dataSet)