title: Pandas `to_excel` set font name
body: <p>Is it possible to set the font name with pandas' excel writer? </p>
  
  <p>Here is my attempt:</p>
  
  <pre><code>import pandas as pd
  from pandas.io.excel import ExcelWriter
  
  df = pd.DataFrame([[1,2,3],[4,5,6]])
  writer = ExcelWriter("test.xlsx")
  writer.set_font_name("Arial")  # this would be ideal, but no such method exists
  
  format = writer.book.add_format({"font_name": "Arial"})
  df.to_excel(writer)  # format is not applied. Need to pass `format` object somewhere
  
  writer.close()
  </code></pre>
  
  <p>Where can I pass the <code>xlsxwriter.format.Format</code> object once it has been created?</p>