Document how to configure options that don’t take an argument
Close the player’s redirected input and output streams

This avoids ResourceWarning warnings in Python 3.

Also, close the pipe or HTTP server before killing the player process.
Closing the input pipe to a process signals an end-of-file condition, and
some players will then terminate of their own accord. This was tested with
MPV, M Player, and VLC with “vlc://quit” at the end of its playlist.
Close the error output stream once it has been passed to the subprocess

Avoids a DeprecationWarning in Python 3.
Close new pipe to background process immediately

Otherwise it would be left open for at least the lifetime of the process
object, and garbage collection would trigger a ResourceWarning.

Also rename the “stdin” variables to be less confusing.