Revision 921

I have done some clarification on functions that allow to access individual data point values in a Data object. 
The term "data point number" is always local on a MPI process and referes to the value (data_point_in_sample, sample)
as a single identifyer (data_point_in_sample + sample * number_data_points_per_sample). a "global data point number"
referes to a tuple of a processour id and local data point number.

The function convertToNumArrayFromSampleNo has been removed now and convertToNumArrayFromDPNo renamed to getValueOfDataPoint.
There are two new functions:

   getNumberOfDataPoints
   setValueOfDataPoint

This allows you to do things like:

  in=Data(..)
  out=Data(..)
   for i in xrange(in.getNumberOfDataPoints())
       in_loc=in.getValueOfDataPoint(i)
       out_loc=< some operations on in_loc>
       out.setValueOfDataPoint(i,out_loc)


Also mindp  is renamed to  minGlobalDataPoint and there is a new function getValueOfGlobalDataPoint. While in MPI the functions getNumberOfDataPoints and getValueOfDataPoint are working locally on each process (so the code above is executed in parallel).
the latter allows getting a single value across all processors.