title: Dealing with spaces and "weird" characters in column names with dplyr::rename()
body: <p>I have table with difficult headers like this:</p>
  
  <pre><code>  Subject  Cat Nbr  Title       Instruction..Mode!
  1 XYZ      101      Intro I     ONLINE
  2 XYZ      102      Intro II    CAMPUS
  3 XYZ      135      Advanced    CAMPUS
  </code></pre>
  
  <p>I would like to rename the columns with <code>dplyr::rename()</code></p>
  
  <pre><code>df %&gt;%
   rename(subject = Subject, 
          code = Cat Nbr, 
          title = title, 
          mode = Instruction..Mode!)
  </code></pre>
  
  <p>But I am getting an <code>Error: unexpected symbol in:</code></p>
  
  <p>How might I reconcile this?</p>