Fixed: closefd flag should only means closefd

Closing source is part of another process. We don't expect the source of
the pipe to be closed when the end of the pipe is closed.

Also: __del__() wasn't defined but if a fileobj is deleted, it should be
closed first (like a regular fileobj in CPython).
Fixed: 7-zip, ghost process issue is solved

It should be now cleanly closed.
Fixed: rar, ghost process issue is solved

It should be now cleanly closed.
Fixed: ExternalPipe should close properly

Closing the filebobj actually close the stdout of the subprocess. But,
if the process is still alive, it tries to terminate it and wait.
Release 2.0