Polish translation update. Thanks Mar!

Here's the second part of my translation, hoping it will be usefull.
In a spare time I'll try to do some more. :)
Add HTML elements to ElementInfo from HTMLNode rather than maintaining a separate list, and hence fix CSS not recognising iframe as an element.
Merge branch 'master' into next
Fix assuming it's a SaltedHashFreenetStore, we don't need to cast now; fixes a mostly harmless ClassCastException on first startup.
Build 1436