Hard cord to file descriptors of stdin, stdout and stderr.

It could cause error to find file descriptor from sys.stdin, sys.stdout
sys.stderr if they are closed.
What is more, daemon(3) is hard corded, too.
Version up to 1.0.
Update pre-commit hook.

Version up pip tool version, add doc8 check and make check strict.
Update comments and documents and pep8 and doc8.
Update testing version of setup.py.