title: regex search for datatable in Rmarkdown
body: <p>[R 3.5.1, DT 0.4]</p>
  
  <p>Here's some sample Rmarkdown code</p>
  
  <pre><code>```{r}
  set.seed(100)
  dt &lt;- data.table(col1=replicate(100, paste(sample(letters,5),collapse='')),
          col2=sample(1:10,100,replace=TRUE))
  DT::datatable(dt, options=list(regex=TRUE)))
  ```
  </code></pre>
  
  <p>Based on the <a href="https://rstudio.github.io/DT/007-search.html" rel="nofollow noreferrer">docs</a>, it seems like this should allow for regular expression searches in the table.  I would like to filter on rows for which column <code>col1</code> begins with <code>i</code>.  So, I entered <code>^i</code> in the search box and I get no rows in the output.  Do I need to set something else?</p>