Backport fixes for two nested scopes bugs.

Backport fixes for two nested scopes bugs.

frameobject.c: make sure free and cell vars make it into locals, which
    makes eval work.

bltinmodule.c & ceval.c: make sure a code object with free variables
    that is passed to exec or eval raises an exception.

Also duplicate the current trunk test suite in the 2.1 branch, except
for certain necessary changes: different warnings raised by 2.1, need
for __future__.