Fix typo debian install doc

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Merge pull request #1754 from Chocobozzz/patch-1

Fix typo debian install doc
latest translations
fix drag drop
render preview on image upload
closes #1729
pass err through
prevent a user from downvoting if at negative rep
added lang strings for not having enough rep to downvote
use admin setting for downvote privileges, closes #1757
closes #1752