Capture C-level output in context managers

 A common task in Python (especially while testing or
 debugging) is to redirect sys.stdout to a stream or a file while
 executing some piece of code. However, simply "redirecting stdout" is
 sometimes not as easy as one would expect. In particular, things
 become interesting when you want C code running within your Python
 process (including, but not limited to, Python modules implemented as
 C extensions) to also have its stdout redirected according to your
 wish. This turns out to be tricky and leads us into the interesting
 world of file descriptors, buffers and system calls.
 .
 This package supports redirecting this output in a straightforward way
 using a context manager.