title: Open a Workbook with XLWINGS without making it visible
body: <p>I am starting to use XLWings (not that I like Excel, at all, but it is something I HAVE TO do). The thing is that I cannot find the way to make Python open a Workbook without showing it.</p>
  
  <p>It seems the constructor for Workbooks in the old XLWings 0.6.4 was xlwings.Workbook, and one of the arguments was a flag 'app_visible' (see <a href="http://docs.xlwings.org/en/v0.6.4/api.html" rel="noreferrer">http://docs.xlwings.org/en/v0.6.4/api.html</a>). </p>
  
  <p>However, in the new v0.9.2 Workbook has been replaced by Book, and Book does not have any such flag (<a href="http://docs.xlwings.org/en/stable/api.html" rel="noreferrer">http://docs.xlwings.org/en/stable/api.html</a>). The App object does have it, and I thought that was the way to go. So I coded:</p>
  
  <pre><code>import xlwings as xw
  
  app = xw.App(visible=False)
  filename = os.path.join(PATH_EXCEL_SAMPLES, r"rangosConDatos_sample01.xls")
  book = xw.Book(filename)
  # Do stuff with the info in the book
  book.close()  # Ya puedo cerrar el libro.
  app.kill()
  </code></pre>
  
  <p>But, regretably, when</p>
  
  <pre><code>book = xw.Book(filename)
  </code></pre>
  
  <p>is executed the 'visible' attribute of app suddenly becomes True, and the book is shown. I do not know if this is a desired feature or an unexpected behaviour. Anyway, any ideas how should I do it?</p>