Resolves#597
rscadd: "Non-wizards using wizard items may experience fun stuff."
tweak: "Mental focus damage level's have returned to old-code, to better compete with Mutate."
bugfix: "Mental focus staff has had its area of effect mode returned."
Removes can_fire() and moves some of it's functionality into
get_next_projectile(), which was renamed to consume_next_projectile() to
indicate the possibility of side-effects.
Also renamed flag var to check_armour
