Improve QUEST_ITEM handling, etc.
Improve QUEST_ITEM handling, etc.

Removed all remaining instances of CAPTIVE and ARTIFACT, modified
"deinit_quest" to reset relevant "g_player" data members (previously
handled in "init_quest"), and ensured "deinit_quest" is called when it
should be from the "show_scroll" function.

theDrake/pebblequest,theDrake/pebblequest