Backlog: Support streaming

[milesgranger]

No description provided.

[milesgranger]

Putting this on the back-burner until it's desired to have by someone.

Because pyO3 does not have a native representation of a file-like object from Python's cffi, it requires multiple calls into Python from Rust which ends up having a significantly slower performance compared to other alternatives.

[martindurant]

This was a cool request - is there an issue on py03 tracking it? In fact, I don't see how to use pyo3 to call the python C API at all, but I suppose you can just declare it as an external library?

[milesgranger]

I was mainly looking at this issue: PyO3/pyo3#933, but haven't gotten back to playing with this. Possible maybe to implement a buffer protocol in a Rust type that Python can have ownership of. 🤔 But so far as

with open(...) f: 
    sweet_rust_function(f)

doesn't seem like an option right now, unless I misunderstand. But again, will have to look at it in more depth.

[milesgranger]

closing in favor of #45