Reuse HTTP(S) connections while downloading

chanarch.py (Downloader):
  __init__():
    Use connection/server instead of files
  __del__():
    (New) Close the connection on destruction
  set_download():
    Removed.
  set_server():
    (New) Set the server information
  close():
    (New) Close the connection
  download():
    Require filename and server filename as arguments
    Use httplib/http.client to save and reuse connections

chanarch.py (ChanThread):
  download_files():
    Use new Downloader methodology