Statistics now work on scalar values (0d arrays)

For variables who shape is "0" (that is, a simple scalar value), statistics calculations now work.  Although many of the statistics are silly, this is useful for report generation.

Implementation: DataObject has a new function "holding_array" which in most cases returns itself. But if self.data.shape==0, it returns a copy of itself with self.data's scalar value tossed into a single element array.  Now that the data is an array, as expected, the statistics code works fine.