Fix for issue #71 where tooltip behaves incorrectly when steps === true. The change checks for this condition and looks up the correct values from item.series.datapoints.points.
Merge pull request #1 from charithtangirala/Incorrect_Tooltip_Steps_71

Fix for issue #71 where tooltip behaves incorrectly when steps === true....
Merge pull request #78 from charithtangirala/master

Show tooltips with correct data for steps