es.po: translation for LyX 2.1 from Ignacio
Spanish Additional.lyx: translations for LyX 2.1 from Ignacio
Spanish Additional.lyx: fix a wrong language tag
German UserGuide.lyx: fix a typo spotted by Stephan
German UserGuide.lyx: fix a typo spotted by a user
changes from lyx.org

git issue: can't see why this needs a commit.