Clean up the unknown layout stuff some more. Please test to make sure this works...

Clean up the unknown layout stuff some more. Please test to make sure this works with translated layout names, especially when one of them is "unknown". The use of "unknown" with RTL is also wrong, probably, as it will appear on the wrong side. But I'm not sure how to fix that.

BTW, to create a file with an "unknown" layout for testing, just take any LyX file, open it with vi, and replace something like:
\begin_layout Section
with
\begin_layout BlubberStuff
That's probably unknown. ;-)

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@25671 a592a061-630c-0410-9148-cb99ea01b6c8