AlignmentFile from String or StringIO support

[MauroIb]

I need to create an AlignmentFile obj from a SAM file that I have stored in a string. This is part of a workflow where I run several steps using subprocess.run() and catch their stdout. I am looking for ways of working without making temporary files.

I see that AlignmentFile does not support StringIO, but allows for stdin. I think I can to patch into stdin using standard python tools, but a way to directly feed a string would be great.