Build dataset with row-wise data

[abeham]

Currently the dataset only accepts data in column format in its constructor. The dataset would be easier to use if it would accept row-wise data in the constructor.

Maybe we can create static methods instead of constructor methods like Dataset.FromRowData(double[,] data) and Dataset.FromRowData(IEnumerable<IList> data).

[abeham]

Maybe using some kind of helper function:

    private IEnumerable<IList> Transpose(IEnumerable<IList> data) {
      var transposed = new List<IList>();
      var iter = data.GetEnumerator();
      if (!iter.MoveNext()) return transposed;
      for (var d = 0; d < iter.Current.Count; d++)
        transposed.Add(new ArrayList());
      do {
        for (var d = 0; d < iter.Current.Count; d++)
          transposed[d].Add(iter.Current[d]);
      } while (iter.MoveNext());
      return transposed;
    }

[abeham]

r16820: Implement static methods to build dataset from row-wise data and added unit test

[jkarder]

r16821: fixed namespace and type name of DatasetTest

[gkronber]

Reviewed r16820 and r16821 together with jkarder.

[abeham]

r17113: merged to stable (16820, 16821)