remove newly imported modules after script execution

[fragmuffin]

addresses issue #102

[jmwright]

Thanks!

[fragmuffin]

Hmm... just a "heads up", it's possible this has introduced a bug.

It occurred for me when I still had the logging stuff in my cqparts library in the __init__.py file.
I spent an hour on it and couldn't figure out what the problem was

Symptom
Script runs correctly the first time, but when it's run a second time it throws an exception.
For me, the exception was raised on code similar to...

import logging

print("IMPORTED: %s" % __name__)

def do_stuff(errlevel, msg):
    if errlevel >= logging.ERROR:
        print(msg)

1. when run the first time, it would work, and "IMPORTED" was printed
2. on the second run, "IMPORTED" was printed, so the assumption is logging was imported, but the if line raised:

AttributeError: 'NoneType' object has no attribute 'ERROR'

After an hour of scratching my head, even using rpdb to debug, and things still didn't make any sense.
I ended up removing the duplicated logging code from my library, and it's been behaving beautifully ever since.

• Likelyhood : LOW
• Impact : HIGH