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
Fix OrderedGlobalDeclarations

if a calls b and b calls b, a has greater weight than b. They used to be the same with the previous code.
Remove usedef + globals

When a global is used in a function before being assigned, it would raise the error "identifier has global linkage and can't be assigned"

Example in test/cases/globals.py