Python tweaks

Hello Thomas,

Please consider applying these two commits to improve the Python scripting. It changes two things:

- the interpreter imports automatically the standard "site" module (Jython 2.5 forgets to import it), which in turn allows a user to customize its setup by writing a script named "sitecustomize.py". It's in such a script that a user should place cide to modify the import paths or other environment variables.

- the console gets the same treatment as the script interpreter (paths, auto-import the site module)

Thanks !

Timothée