title: gnuplot: label x and y-axis of matrix (heatmap) with row and column names
body: <p>I'm absolutely new to gnuplot and did not find a working solution after googling.</p>
  
  <p>I have a data matrix looking something like this:</p>
  
  <pre><code>  A B C D E
  A 0 2 3 4 5
  B 6 0 8 9 0
  C 1 2 0 4 5
  D 6 7 8 0 0
  E 1 2 3 4 0
  </code></pre>
  
  <p>What I would like to do is plotting a heatmap with <code>plot 'result.csv' matrix with image</code>, with the x-axis labeled with A-E and the y-axis labeled with A-E. This matrix does not always have the same size, but the number of row always equals the number of cols and it's always labeled.</p>
  
  <p>Could someone help me out with this? I guess I have to use the <code>using</code> command, but up to now this appears like complete voodoo to me...</p>
  
  <p>Thanks a lot!</p>