title: insert image into text buffer
body: <p>If I place</p>
  
  <pre><code>(insert-image (create-image "/tmp/test.png"))
  </code></pre>
  
  <p>in a buffer, place the cursor after the last parenthesis and evaluate it with <code>C-x C-e</code>, then the image <code>/tmp/test.png</code> is displayed in the buffer:</p>
  
  <p><img src="https://i.stack.imgur.com/Wb2sF.png" alt="enter image description here"></p>
  
  <p>Pretty neat. But,</p>
  
  <ol>
  <li>I had to put the final parenthesis on a separate line, so the image
  is close to the left-hand side of the buffer. Is there a way to hide
  the <code>(insert-image ...)</code> text altogether?</li>
  <li>The text file contains the <code>(insert-image ...)</code> text only, not the
  image. I'm happy with that, but is there a way to tell emacs to
  automatically replace all the <code>(insert-image ...)</code> expressions by
  their corresponding images (after the file is opened) without me having to type <code>C-x C-e</code> after
  each one?</li>
  </ol>