I want to make this "bypass getattr" behavior mandatory for those
operations that currently use it, forcing the issue for other
implementations of Python.  That's a doc change (but an important one!).
 There are probably many random places where the docs imply that getattr
is used where it isn't.

I am not sure that we need a proxy implementation in the stdlib; usually
when proxying there is some intentional irregularity (that's why you're
proxying) and I'm not sure how useful the mix-in class will be in
practice.  We should wait and see how effective it is in some realistic
situations before accepting it into the stdlib.  Also, typetools strikes
me as a horrible name.