turses crashes when config file exists

[booxter]

Issue description

If you start turses without a config file, then it starts fine. But when later you exit it and start again, then it crashes with:

Traceback (most recent call last):
  File "/nix/store/sq21f09xlsm7bjd6vrihl9zg49alsvpr-python3.6-turses-0.3.1/bin/.turses-wrapped", line 12, in <module>
    sys.exit(main())
  File "/nix/store/sq21f09xlsm7bjd6vrihl9zg49alsvpr-python3.6-turses-0.3.1/lib/python3.6/site-packages/turses/cli.py", line 146, in main
    configuration.load()
  File "/nix/store/sq21f09xlsm7bjd6vrihl9zg49alsvpr-python3.6-turses-0.3.1/lib/python3.6/site-packages/turses/config.py", line 504, in load
    self._init_config()
  File "/nix/store/sq21f09xlsm7bjd6vrihl9zg49alsvpr-python3.6-turses-0.3.1/lib/python3.6/site-packages/turses/config.py", line 513, in _init_config
    self.parse_config_file(self.config_file)
  File "/nix/store/sq21f09xlsm7bjd6vrihl9zg49alsvpr-python3.6-turses-0.3.1/lib/python3.6/site-packages/turses/config.py", line 716, in parse_config_file
    self._parse_styles(conf)
  File "/nix/store/sq21f09xlsm7bjd6vrihl9zg49alsvpr-python3.6-turses-0.3.1/lib/python3.6/site-packages/turses/config.py", line 760, in _parse_styles
    conf.get(SECTION_STYLES, style), 'utf-8')
TypeError: decoding str is not supported

This error was fixed in louipc/turses@be0961b?diff=split but it's not part of tool official releases. (Note that the original upstream repo no longer exists; so we should switch to louipc fork of it.

Steps to reproduce

1. nix-env -f . -i python3.6-turses
2. turses
3. close it with "q".
4. turses

Technical details

Please run nix-shell -p nix-info --run "nix-info -m" and paste the
results.

[ihar@dell:~/git/nixpkgs]$ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 4.14.105, NixOS, 18.09.2317.18fec2687c0 (Jellyfish)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.1.3`
 - channels(root): `"nixos-18.09.2317.18fec2687c0"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`