Code review comment for lp:~widelands-dev/widelands/empire04_unused_key_return_on_dismantle

We already had to add some strings for other bug fixes. I think breaking the string freeze for smaller strings is OK, as long as we don't overdo it.

I have addressed all the points in the code review now. We can't check for duplicate keys in Lua tables, because the backend (Eris) or maybe Lua itself already squashes them. So, I have removed all those checks.