Translation bundles are not really ordered by priority

The iterator in java.util.PriorityQueue is not ordered...

The effect of this is that the priority of the translations (e.g. that translations in wiki documents should always have priority over translations in jars – as XWIKI-8881 says) is not respected. For specific values of n (the size of the queue), the order might be the correct one, but in general it's not the correct one (for n=7, for example, the iterator returns the values in broken order).