[IronPython] Importing on another Thread

[Dan Eloff]

> Does it work if you do the imports normally?

Yes. I should have mentioned that these same modules are all imported
successfully on the main thread (but that they still fail to import in
the background if I comment that out)

> Out of interest, why?

Most of my startup time is spent importing, I think I may be able to
shave 30% off that if I can do some of the imports on a background
thread (stdlib modules, some supporting packages.) Of course there
would be no performance improvement on a single core machine, but
those are becoming rarer every day.

-Dan