Importlib update

Importlib has now been (roughly) bootstrapped into Py3K in my py3k-importlib branch. There are some tests that are still failing that I have not tried to fix yet. I also have not removed any C code yet so there is still a chance of some dependency that I don't know about yet.

And there is still the issue of 'warnings' not being a built-in module. Neal Norwitz wrote an initial C version of the critical stuff, but it isn't complete. The biggest issue is that it doesn't pick up anything that is set on 'warnings' itself (e.g., 'filters', 'showwarnings'). That's bad as various attributes in 'warnings' get set externally frequently. My proposed solution is to see if 'warnings' has been imported, and if so use the attributes from there, otherwise fall back on internal C stuff. That way the module is entirely independent of Python code and thus doesn't cause me any bootstrap issues.

Once 'warnings' is built-in I will be able to rip out C code to make sure this whole thing actually works. Then I can fix any bugs I have for importlib itself. That should be it at that point and I should hopefully be able to move my work into Py3K itself.