title: Titles overlapping or going out
body: <p>I'm trying to have 4 plots with a title for each of them and a main title.
  I first tried this code :</p>
  
  <pre><code>set.seed(13);  
  par(mfrow = c(2,2))  
  for(i in 1:4){  
    plot(runif(10), t = "l", lwd = 3)  
    title(main='I have a title for each of the plots') 
  }  
  title(main="This is a very long title which needs to fit on two lines.\nUnfortunately it overlaps the other titles and it's not readible", outer=TRUE, line=-2)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/o7Dr5.png" alt="enter image description here"></p>
  
  <p>I tried making the main title go higher or lower but either it goes out of the screen or overlaps the other titles.</p>
  
  <p>Having larger plots don't help either...</p>
  
  <p>Does anyone have any idea how to sort this out?</p>