eliminate default Module global

This changes the `Module` object to be declared as a local variable now. I'd meant to do this a while back when I first added `EXPORT_NAME` but I forgot until I started reviewing the old onload branch today.

`runner.py` needed an update because now the `Module` will get mangled as it's no longer a global variable.

As well, if an existing Module object exists, it copies off and then restores its properties _after_ the environment initialization to eliminate the need to be so defensive when setting up the environment.

Ran o1, other and browser tests.