Begins turning in a quest to a questgiver. Usable following the
QUEST_PROGRESS event in which it is determined whether the player can complete the quest.
Does not complete the quest turn-in process; after calling this function, the
QUEST_COMPLETE event fires as the questgiver presents rewards (or sometimes only closure to the quest narrative); following that event, the
GetQuestReward() function finishes the turn-in.
See also Quest functions.