Merge "API: i18n for warnings and errors"

diff --cc RELEASE-NOTES-1.29
Simple merge

diff --cc autoload.php
Simple merge

diff --cc docs/hooks.txt
Simple merge

diff --cc includes/specials/SpecialEmailuser.php
Simple merge

diff --cc includes/specials/SpecialUnblock.php
Simple merge

diff --cc languages/i18n/en.json
Simple merge

diff --cc languages/i18n/qqq.json
Simple merge