Update strings.xml

A big update, thanks!
(cherry picked from commit e8000b5)
Remove comment markers around translated string
(cherry picked from commit d306b2c)
Fix errors in pt-BR translation
(cherry picked from commit 5ecce67)
Brazilian portuguese translation and fixes 2

Update and fixes, thanks
(cherry picked from commit 50848b3)
Fixed typo
(cherry picked from commit 2a575e9)
Updated Japanese translation.
(cherry picked from commit 6d88b7d)
Move Japanese translation of the changelog into the correct directory
(cherry picked from commit da09420)
Always include currently opened message in the message list

This should fix various bugs where moving to the next/previous message
didn't work.
Update changelog