Message2088

Optional nested scopes support (as python 2.1b1)

LocalsCompiler becomes obsolete.
Adds few new files.

from __future__ import nested_scopes
does not setup nested scope for the entire session
from an interactive prompt: but the necessary
hooks are already there ...

It passes test_scope from python 2.1b1

and a typical subset of python 2.1b1 regression
tests and the jython regrtest suite
(even with nested scopes logic forced on).

[some corner cases must be clarified together
with python].

-- sP