title: python 3 make subsection for configparser
body: <p>I'm trying to convert one open source project from Python 2  to Python 3 
  Project uses configobj module which is not supported for Python 3.</p>
  
  <p>Project uses subsections in config file. </p>
  
  <p>How to realize similar functionality with configparser module?</p>
  
  <p>e.q.
  configfile.txt is:</p>
  
  <pre><code>[General Log]
  filename = log.txt
  [Thread1]
  filename = thread1.txt
  [[log]]
  filename = thread1_log.txt
  </code></pre>
  
  <p>and with this config file i can do like </p>
  
  <pre><code>from configparser import ConfigParser
  congfile = ConfigParser()
  configfile.read('configfile.txt')
  
  print(configfile['Thread1']['Log']['filename'])
  </code></pre>
  
  <p>should print thread1_log.txt</p>
  
  <p>is it possible to make new class of configparser class to do this?
  Any modules to support this functionality with ython 3</p>