Make the "python" command resemble the standard Python interpreter

[Joel Brobecker]

> But "python" seems rather an intuitive way of doing it.  The existing
> behavior is quite surprising and unintuitive, because it accumulates
> an entire multi-line string without any parsing, and then hands it off
> all at once to Python.  I see no reason to preserve that behavior if
> we have a normal Python interactive interpreter loop.  That loop does
> everything the existing thing does and far more/better, so it should
> replace the old behavior.

I tend to agree. I have wished many times before that the "python"
command without argument would enter the Python interpreter.

-- 
Joel