Rotate before cropping

[timmarkhuff]

Cropping is performed after rotation, which makes it confusing to choose the right cropping parameters if the image has already been rotated. It would be more intuitive to rotate and then crop relative to the rotated frame. This should be as simple as changing the order of the method calls in _process_frame.

    def _process_frame(self, frame: np.ndarray) -> np.ndarray:
        """Apply _crop, _digital_zoom, and _rotate to the provided frame.
        as specified in options."""
        frame = self._crop(frame)
        frame = self._digital_zoom(frame)
        frame = self._rotate(frame)
        return frame

[timmarkhuff]

This was addressed in #53