Fix Types analysis to deal with globals
Remove error when parsing code with globals
Prepare for backend - add C++ changes

For a rough explanation of how this will work, check this out: https://github.com/coyotte508/pythran/wiki/Typing-analysis
Change backend to deal with globals
Add export header and export macros when needed
Fix tutorial example
Add raw euler test cases

So we can test if they work with globals
test_env can capture output of __init__ function