Constructs a new DataTable using a dictionary of the format:

        {field1: [a,b,c],
         field2: [d,e,f],
         field3: [g,h,i]}

        ... which most closely matches the internal representation
        of the DataTable. If it is an OrderedDict, the key order
        will be preserved.

def fromdict(cls, datadict):
        """
        Constructs a new DataTable using a dictionary of the format:

        {field1: [a,b,c],
         field2: [d,e,f],
         field3: [g,h,i]}

        ... which most closely matches the internal representation
        of the DataTable. If it is an OrderedDict, the key order
        will be preserved.
        """
        new_datatable = cls()
        for field, column in datadict.items():
            new_datatable[field] = column
        return new_datatable