title: Vim: Open new explorer tab with the directory of the file you're currently on
body: <p>I'd like to open a new tab with the file explorer set to the directory of the file I have open, instead of the directory I opened vim from. For example,</p>
  <p>If I do:</p>
  <pre><code>~: cd ~/dir1
  ~/dir1: vim dir2/dir3/dir4/file1
  </code></pre>
  <p>Then from inside that window I would like to open a new tab with a file explorer currently showing the contents of <code>~/dir1/dir2/dir3/dir4/</code> (the directory of the file in the currently active tab).</p>
  <p>I have the following mapping set up:</p>
  <pre><code>nnoremap &lt;leader&gt;t :tabnew&lt;CR&gt;:Ex . &lt;CR&gt;
  </code></pre>
  <p>But that just opens the file explorer at <code>~/dir1</code>. How can I edit this key-mapping to pass to <code>:Ex</code> the directory of the file that is currently open?</p>