title: pandas to_csv: ascii can't encode character
body: <p>I'm trying to read and write a dataframe to a pipe-delimited file. Some of the characters are non-Roman letters (`, ç, ñ, etc.). But it breaks when I try to write out the accents as ASCII.</p>
  
  <pre><code>df = pd.read_csv('filename.txt',sep='|', encoding='utf-8')
  &lt;do stuff&gt;
  newdf.to_csv('output.txt', sep='|', index=False, encoding='ascii')
  
  -------
  
    File "&lt;ipython-input-63-ae528ab37b8f&gt;", line 21, in &lt;module&gt;
      newdf.to_csv(filename,sep='|',index=False, encoding='ascii')
  
    File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\core\frame.py", line 1344, in to_csv
      formatter.save()
  
    File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\formats\format.py", line 1551, in save
      self._save()
  
    File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\formats\format.py", line 1652, in _save
      self._save_chunk(start_i, end_i)
  
    File "C:\Users\aliceell\AppData\Local\Continuum\Anaconda3\lib\site-packages\pandas\formats\format.py", line 1678, in _save_chunk
      lib.write_csv_rows(self.data, ix, self.nlevels, self.cols, self.writer)
  
    File "pandas\lib.pyx", line 1075, in pandas.lib.write_csv_rows (pandas\lib.c:19767)
  
  UnicodeEncodeError: 'ascii' codec can't encode character '\xb4' in position 7: ordinal not in range(128)
  </code></pre>
  
  <hr>
  
  <p>If I change to_csv to have utf-8 encoding, then I can't read the file in properly:</p>
  
  <pre><code>newdf.to_csv('output.txt',sep='|',index=False,encoding='utf-8')
  pd.read_csv('output.txt', sep='|')
  
  &gt; UnicodeDecodeError: 'utf-8' codec can't decode byte 0xb4 in position 2: invalid start byte
  </code></pre>
  
  <p>My goal is to have a pipe-delimited file that retains the accents and special characters.</p>
  
  <p>Also, is there an easy way to figure out which line read_csv is breaking on? Right now I don't know how to get it to show me the bad character(s).</p>