support for users not logged in

Hi, I previously did a version of this plugin supporting language switching for users who are not logged in, simply by using a cookie pll_language (compatible with Polylang).
Noting the recent updates I was going to reapply the change to updated version: having re-found the github project I wondered whether you would welcome a pull request for this.
– Normally I’d submit an issue on github to propose but the issues seem to be turned off on the project so thought I’d mention it here.