[Cython] Fix for #196 (for loop bug)

[Dag Sverre Seljebotn]

Dag Sverre Seljebotn wrote:
> What you do is call "code.funcstate.allocate_temp(integer_type_of_step)" 
>   

To be slightly more helpful here, I believe the exact call would be

code.funcstate.allocate_temp(step.type)

I think step will be a "coercion node" if step is a Python object so you 
don't need to worry about refcounts etc. (but do include functions 
returning both Python and C types as "step" in your tests).

Thanks for doing this!

Dag Sverre