Improve interface

Added enable() and disable() functions to __init__, which install all
the objects needed. Customization possible. Also minor improvements in
connection with the interface.
Add fileno() and isatty() to streams

Windows console raw streams now have fileno() returning the standard
fileno and isatty() returning True. This changes the behavior of input()
function – it now calls readline hook rather than using the modified
streams directly. So we have autocompletion even within input(), on the
other hand we allways need custom readline hook for Unicode input().
Fix case of sys.stdin == None

Explicit check of stream == None was added so streams.enable() doesn't
raise exception when the streams are None (as in case of IDLE).
Add sitecustomize.py

Sample sitecustomize file was added.