title: Highcharts tooltipformat for each series?
body: <p>I m using dotnetHightcharts</p>
  
  <p>BasicColumnChart</p>
  
  <pre><code>public static Highcharts BasicColumnChart(Series[] Series, string[] Categories, string Title = "", string SubTitle = "", string XAxisTitle = "", string YAxisTitle = "", string ToolTipFormat = "", string YAxisLabel = "")
  {
      Highcharts chart = new Highcharts("chart")
          .InitChart(new Chart { DefaultSeriesType = ChartTypes.Column, Height = 300 })
          .SetTitle(new Title { Text = Title })
          .SetSubtitle(new Subtitle { Text = SubTitle })
          .SetXAxis(new XAxis { Categories = Categories })
          .SetYAxis(new YAxis
          {
              Min = 0,
              Title = new YAxisTitle { Text = YAxisTitle },
              Labels = new YAxisLabels
              {
                   Formatter = @"function() { return this.value +' " + YAxisLabel + "';}"
              }
          })
          .SetLegend(new Legend
          {
              Layout = Layouts.Vertical,
              VerticalAlign = VerticalAligns.Top,
              Align = HorizontalAligns.Right,
              Shadow = true,
              BackgroundColor = ColorTranslator.FromHtml("#FFFFFF"),
              Floating = true
          })
          .SetTooltip(new Tooltip { Formatter = @"function() { return ''+ this.x +' - '+ this.y +' " + ToolTipFormat + "'; }" })
          .SetPlotOptions(new PlotOptions
          {
              Column = new PlotOptionsColumn
              {
                  PointPadding = 0.2,
                  BorderWidth = 0
              }
          })
          .SetSeries(Series);
  
      return chart;
  }
  </code></pre>
  
  <p>I can set same tooltipFormat for every series with following line:</p>
  
  <pre><code>.SetTooltip(new Tooltip { Formatter = @"function() { return ''+ this.x +' - '+ this.y +' " + ToolTipFormat + "'; }" })
  </code></pre>
  
  <p>Above code output : <code>date - value tooltipFormat</code></p>
  
  <p>But I want to show different format for each series. Why do I want this, Because I want to show different data that has different unit, for example:</p>
  
  <pre><code>value[0] = 220 V    //Volt
  value[1] = 5 A      //Ampere
  ...
  value[15] = 1200 kW //Kilowatt
  </code></pre>
  
  <p>there are a lot of example about this topic but, these examples only change text. My data views like this:</p>
  
  <pre><code>NAME     VALUE    UNIT
  
  Volt     220      V
  Ampere     5      A
  ....
  </code></pre>
  
  <p>I want to change tooltipFormat for each series dynamicly. I want to add <code>UNIT</code> field dynamicly. How can I do this?</p>
  
  <p>Thanks.</p>