My current patch ends up with O(n) deletion, which won't fly, so I'm refactoring.  While I'm at it I'm also planning on using the BSD queue.h doubly-linked list rather than the one that I rolled.  I'm also going to pull the ordered dict implementation into it's own source file.  However, these things should not have much of an impact on most of the code I've already written.  I anticipate that the changes won't translate into a further large volume of work.

In talking to Raymond, he emphasized the importance of making sure we avoid reentrancy problems.  I'll be double-checking that and likely making use of the GIL in a couple spots.

While the bulk of the implementation is complete, the remaining work to do here is what I've described above, along with more testing.  An orthogonal problem is addressing the problem of the concrete dict API.  I'll bring that up separately when this issue is basically done.