title: gnuplot - no space between graph and png image edge
body: <p>How to create a .png image in <code>gnuplot</code> to see no spaces between graph itself and image edges.
  I use</p>
  
  <pre><code>set terminal pngcairo size 800,600 enhanced 
  </code></pre>
  
  <p>I want exactly 800x600 image. And want all 0X axis correspond to [0..800] interval, and all 0Y correspond to [0..600] interval.</p>