PyO3 0.8.0

Added

• module argument to pyclass macro. #499
• py_run! macro #512
• Use existing fields and methods before calling custom getattr. #505
• PyBytes can now be indexed just like Vec<u8>
• Implement IntoPy<PyObject> for PyRef and PyRefMut.

Removed

• IntoPyObject was replaced with IntoPy<PyObject>
• #[pyclass(subclass)] is hidden a unsound-subclass feature because it's causing segmentation faults.

Fixed

• More readable error message for generics in pyclass #503

Changed

• Implementing the Using the gc parameter for pyclass (e.g. #[pyclass(gc)]) without implementing the class::PyGCProtocol trait is now a compile-time error. Failing to implement this trait could lead to segfaults. #532
• PyByteArray::data has been replaced with PyDataArray::to_vec because returning a &[u8] is unsound. (See this comment for a great write-up for why that was unsound)
• Replace mashup with paste.
• GILPool gained a Python marker to prevent it from being misused to release Python objects without the GIL held.