Bugfix/side effects

[atait]

1. Supported pytest framework, in case it is preferred over nose
2. Transformer context is now derived from a shallow copy of __globals__

• we don't want a function closure variable to be added to module globals

If a is defined in globals, it makes its way to context, and then

for a in range(3):
    x = a

is collapsed to

for 0 in range(3):
    x = 0

It might be possible to support this, but I'm not sure how, and it should probably not be allowed.

[coveralls]

Pull Request Test Coverage Report for Build 106

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.1%) to 85.924%

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Totals
Change from base Build 104:	0.1%
Covered Lines:	1056
Relevant Lines:	1229

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💛 - Coveralls