Name: make_killable - make a player killable

Syntax:
	make_killable()

Description:
	The make_killable makes a player killable. The player then can kill
	other killable players and can get killed by them. This status will
	be automatically resetted if the player dies.

Return value: none

Examples:
	this_player()->make_killable();

See also: player/query_killable