title: gnuplot plotting multiple errorbars depending on first column
body: <p>I have a data file with the following format: 
  col1: plot[0-9]+
  col2: x
  col3: y
  col4: delta</p>
  
  <p>For example: </p>
  
  <pre><code>plot0, 1, 1, 2
  plot1, 1, 2, 2
  plot0, 2, 2, 1
  plot1, 2, 3, 2
  </code></pre>
  
  <p>I am trying to plot a yerrorbars for each plotX of the first column with separated legend and color. </p>
  
  <p>A none scalable example would be: </p>
  
  <pre><code>plot 'ex.dat' using 1:2:3 with yerrorbars, 'ex1.dat' using 1:2:3 with yerrorbars
  </code></pre>