The settingsReader.py file should fall back to the config file shipped with Retiled if the requested key isn't present in the version in `~/.config/Retiled/RetiledSettings/configs/` even if there is a config file there.

[DrewNaylor]

This way it's easier for projects to change the defaults while also keeping a safe backup setting in the code so everything doesn't break if there's no config file present at all.

[DrewNaylor]

I also need to ensure user settings can be written to the config file in the home directory just in case the default one is deleted or missing for some reason.