title: RMarkdown: UTF-8 works with Knit button but not with render()
body: <p>I'm working in RMarkdown, trying to render a document that has some UTF-8 characters in it. When I push the "Knit" button in RStudio, everything works great. But when I use the render() function, the UTF-8 gets lost. Here's a short snippet of reproducible code:</p>
  
  <pre><code>---
  output: html_document
  ---
  
  Total nitrogen (µg/L)
  
  Water temperature (°C)
  </code></pre>
  
  <p>Pushing the Knit button gives me the correct output, whether I view it in RStudio or in Chrome. But if I render the file with render(), I get: </p>
  
  <blockquote>
    <p>Total nitrogen (Âµg/L)</p>
    
    <p>Water temperature (Â°C)</p>
  </blockquote>
  
  <p>I'm working in Windows, which may be the source of much of the problem. Here's my locale info.</p>
  
  <pre><code>Sys.getlocale("LC_ALL")
  [1] "LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252"
  </code></pre>
  
  <p>I've tried adding a code chunk with "options(encoding = 'UTF-8')" but it doesn't help. I'm using pwalk() to generate 36 reports automatically with different parameters, so I need to get this working with render().</p>