Fixed query to actually work for multiple language orders, by joining on translation ids between tables instead of node ids.
Added a new option to allow overriding of the specified language order: whenever the current language is equal to the default site language, it will ignore the order specified, and will just return content of the default language. (Thanks hugronaphor)
To do this, also had to wrap the join into a sub query, because domain / node_access added exists clauses to the left joined node tables. The sub query fixes that for now.
Make the priority list hidden, when list is not selected.
Add option not to include content without translations (does not belong to a translation set, aka tnid = 0).
By default, it is enabled.