Call countData

In 'HistogramCreate.run' a histogram class is created but the histogram data does not seem to be generated.  It seems a call to 'countData' is needed to generate the histogram of the input.
Threshold op now passed to map op

Previously a threshold of type T was passed to the map op.  However the map needs a fucntion as the third input parameter.
Threshold converted from bin number to gray level

In Otsu.java getThreshold, the threshold is calculated as a bin number.  Added code to convert it to a gray level.