func (set *DataSet) ColumnNamed(columnName string) *Column {
	for _, column := range set.Columns {
		if columnName == column.Name {
			return column
		}
	}
	return nil
}
ColumnNamed returns the ColumnInfo for a column given it's name, or nil if no column
with that name exists in the data set
package idrf
import (
	"fmt"
)
type DataSet struct {
	DataSetName string
	Columns     []*Column
	TimeColumn  string
}
func (set *DataSet) String() string {
	return fmt.Sprintf("DataSet { Name: %s, Columns: %s, Time Column: %s }", set.DataSetName, set.Columns, set.TimeColumn)
}