Name: query_data - get stored data from a player

Syntax:
	mixed query_data()

Description:
	The query_data function returns data once stored in the player with
	store_data in. Note that only the same file that stored the data can
	query it.

Return value:
	The data stored in the player for that object if there are any,
	else 0.

Examples:
	mixed data;
	data = this_player()->query_data();
	if (data != "club member") return write("You're not a member.\n");

See also: build/player_data, player/store_data, player/remove_data