title: Pandas escape carriage return in to_csv
body: <p>I have a string column that sometimes has carriage returns in the string:</p>
  
  <pre><code>import pandas as pd
  from io import StringIO
  
  datastring = StringIO("""\
  country  metric           2011   2012
  USA      GDP              7      4
  USA      Pop.             2      3
  GB       GDP              8      7
  """)
  df = pd.read_table(datastring, sep='\s\s+')
  df.metric = df.metric + '\r'  # append carriage return
  
  print(df)
    country  metric  2011  2012
  0     USA   GDP\r     7     4
  1     USA  Pop.\r     2     3
  2      GB   GDP\r     8     7
  </code></pre>
  
  <p>When writing to and reading from csv, the dataframe gets corrupted:</p>
  
  <pre><code>df.to_csv('data.csv', index=None)
  
  print(pd.read_csv('data.csv'))
    country metric  2011  2012
  0     USA    GDP   NaN   NaN
  1     NaN      7     4   NaN
  2     USA   Pop.   NaN   NaN
  3     NaN      2     3   NaN
  4      GB    GDP   NaN   NaN
  5     NaN      8     7   NaN
  </code></pre>
  
  <h2>Question</h2>
  
  <p>What's the best way to fix this? The one obvious method is to just clean the data first:</p>
  
  <pre><code>df.metric = df.metric.str.replace('\r', '')
  </code></pre>