title: kill subprocess when python process is killed?
body: <p>I am writing a python program that lauches a subprocess (using Popen).
  I am reading stdout of the subprocess, doing some filtering, and writing to
  stdout of main process.</p>
  
  <p>When I kill the main process (cntl-C) the subprocess keeps running.
  How do I kill the subprocess too? The subprocess is likey to run a long time.</p>
  
  <p>Context:
  I'm launching only one subprocess at a time, I'm filtering its stdout.
  The user might decide to interrupt to try something else.</p>
  
  <p>I'm new to python and I'm using windows, so please be gentle.</p>