title: Gnuplot, how to include a space character in key titles?
body: <p>I want to use key titles like "Best F" "Worst F" for a gnuplot 4.4 graph, when reading the data from a file, but I can't figure out how to put the space, e.g.:</p>
  
  <pre><code>Generation Best_F Worst_F Average_F
       5        4     9         5
       4        3     9         4
  </code></pre>
  
  <p>I tried writing in the file "Best F", "Best%20F" "Best\ F" but they get split, when read as column headers, or I get the ugly looking "%20".</p>
  
  <pre><code>plot for[col=2:4] data.dat using 1:col title columnheader(col)
  </code></pre>
  
  <p>Or is there a way to do a character substitution, like "Best_F"%" "->"Best F"? replace("_", "\ ", columheader(col))?</p>
  
  <p>I am using terminals wxt and pngcairo (no latex).
  Thanks</p>