[Pyrex] Sequence patches from Paul Prescod

[Jim Kleckner]

Looking at Pyrex-generated code, I see boxing of integer
types when indexing into sequence types that seems avoidable.

After digging, I noticed Paul Prescod's patches for sequences
that are documented here:

 http://www.prescod.net/python/pyrexopt/pyrex_sequences.diff

What was the status of this discussion?  It seems like a
relatively clean patch.  Is there some reason I should avoid it?

Jim