title: Split string with non greedy regex via strsplit
body: <p>I am facing a problem with regex and strsplit. I would like to split the following <code>x</code> string based on the second <code>:</code> symbol</p>
  
  <pre><code>x &lt;- "26/11/19, 22:16 - Super Mario: It's a me: Super Mario!, but also : the princess"
  </code></pre>
  
  <p>and obtain then something like this</p>
  
  <pre><code>"26/11/19, 22:16 - Super Mario"
  " It's a me: Super Mario!, but also : the princess"
  </code></pre>
  
  <p>I am using by using <code>strsplit</code> with the following regular expression that in based on my little know-how should reason like <em>"select ONLY the colon symbol followed by a space and preceded by ONLY letters"</em>.</p>
  
  <p>I tried to make the regex non greedy with the <code>?</code> symbol but clearly I am missing something and the result does not work as expected because it includes also <code>me:</code> in the splitting operation.</p>
  
  <p>It is essential I think to have a non greedy operator, because the string here is just an example I do not have always the word <code>Mario</code> of course.</p>
  
  <pre><code>strsplit(x, "(?&lt;=[[:alpha:]]):(?= )", perl = TRUE)
  </code></pre>
  
  <p>Thank you in andvance!</p>