Information about a quest. Right now it only checks if the quest has been completed, and can provide you a link to the quest on WoWhead.
Usage:
/quest <AchievementLink, QuestLink or QuestId>
When using a numeric quest-id, add "link" after for a popup with wowhead link
Examples:
/quest [Lost Mail]
/quest 41368
/quest 41368 link