function updateTooltip(dataPoint, xPosition, yPosition) {
            updateContent(dataPoint);
            updatePositionAndSize(dataPoint, xPosition, yPosition);
        }
Updates tooltip title, content, size and position
sorts by alphatical name order if not forced order given

@param  {lineChartPointByDate} dataPoint  Current datapoint to show info about
@param  {Number} xPosition           Position of the mouse on the X axis
@return void
@private