title: Automatic line break in ggtitle
body: <p>Is there a way to force an <em>automatic</em> line break in the <code>ggtitle</code> command?</p>
  <p>As part of a shiny application I use different plots with an input variable for the title.
  Unfortunately, some of these variable values are too long to be displayed.</p>
  <p>I came across one possibility by inserting <code>\n</code> (or a line break) manually in advance (Details here: <a href="https://stackoverflow.com/questions/28023679/improve-editing-of-multiline-title-in-ggplot-that-uses-n-and-extends-far-to-the">Improve editing of multiline title in ggplot that uses \n and extends far to the right</a>). There, something like <code>ggtitle(paste(&quot;&quot;, title, &quot;&quot;, sep = &quot;\n&quot;))</code> would be suggested.</p>
  <p>Since including <code>\n</code> would be error prone as well as not flexible for different plot sizes I´m looking for another possibility.</p>
  <p>Here is an minimal working example (adapted from lawyeR question linked above):</p>
  <pre><code>DF &lt;- data.frame(x = rnorm(400))
  title_example &lt;- &quot;This is a very long title describing the plot in its details. The title should be fitted to a graph, which is itself not restricted by its size.&quot;
  plot &lt;- ggplot(DF, aes(x = x)) + geom_histogram() +
    ggtitle(title_example)
  </code></pre>
  <p>You can find a image here: <a href="https://i.stack.imgur.com/6MMKF.jpg" rel="noreferrer">https://i.stack.imgur.com/6MMKF.jpg</a></p>
  <p>Do you have an idea how to e.g. adapt the <code>sep = </code> operator to break lines automatically or are there maybe packages/ workarounds? Thanks!</p>