Fixed exception when files were updated while script was running.

m_UpdatedFiles was being updated while it was still being used by the
script thread.  Instead, copy the list, clear it out, and have the
script thread process the copy.
Trying to fix annoying Import Exceptions (which actually don't prevent the program or scripts from working)

IronPython throws Import Exceptions for every single import, even though
it imports them and the script works fine.  It's annoying while trying
to debug, and I'm sure it hurts the scripts performance while importing
things.  Issue is still not fixed, but these were things I was trying
that I'm making sure to backup.  And they can't hurt.