[LyX/master] port the recent fixes and update of layouttranslations to master

[Uwe Stöhr]

commit b04e6eae3bd51f25ad88ef63e80f03905cece08d
Author: Uwe Stöhr <uwesto...@lyx.org>
Date:   Tue Feb 20 20:42:36 2018 +0100

    port the recent fixes and update of layouttranslations to master

 README.localization           |   15 +-
 lib/layouttranslations        |   14 +-
 lib/layouttranslations.review |    4 +-
 po/ar.po                      | 1563 +++++++++++++++++++----------------------
 4 files changed, 744 insertions(+), 852 deletions(-)