Thinkfan underwent some major changes and the config file
is now based on YAML. This commit contains a number of changes:
- rewrite the module to output the new format;
- add a `settings` option, following RFC 0042[1];
- add fancy type-checking for the most critical options
- use upstream systemd units (which fix the resume issue)
[1]: https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md
02b872310d