title: Split a list column into multiple columns
body: <p>I have a data frame where the last column is a column of lists. Below is how it looks:</p>
  <pre><code>Col1 | Col2 | ListCol
  --------------------------
   na  |  na  | [obj1, obj2]
   na  |  na  | [obj1, obj2]
   na  |  na  | [obj1, obj2]
  </code></pre>
  <p>What I want is</p>
  <pre><code>Col1 | Col2 | Col3  | Col4
  --------------------------
   na  |  na  | obj1  | obj2
   na  |  na  | obj1  | obj2
   na  |  na  | obj1  | obj2
  </code></pre>
  <p>I know that all the lists have the same amount of elements.</p>
  <p>Edit:</p>
  <p>Every element in ListCol is a list with two elements.</p>