From 06f58149

When set to True prevents the regeneration of the mirrorlist if
pacman-mirrors is invoked with the --no-update argument.
Useful if you don't want the mirrorlist regenerated after a
pacman-mirrors package upgrade.

Rewrite some comments

needed for interactive mode

it's only a way to invoke pacman-mirrors without any argument

The fields of the server are a dictionary instead of a list.

Check for key/value when commenting OnlyCountry, write the default value (empty)
Add OnlyCountry at the end of file if can't find key OnlyCountry

Strip whitespaces around key and value when parsing config file

- Better error handling and error messages.
- Use "with ... as ...:" if possible.
- Detect Gtk using importlib instead hardcoded file path.
- Separate in another function writing the mirrorlist in interactive mode.
- Use underscores instead of CamelCase following PEP8.
- Use builtin timeout instead of signal module.