function:
	potion_effect(), it_use2.cc
spells:
	a number of enchantment spells use the function potion_effect() to affect the player. These spells pass their enchantment power, which is usually 3*power/2
	power cap: 150
real potions: 
	as spells with power 40


healing: 
	heals 5-12
	cures poison, rotting, disease and confusion
	if at full hp: restore 1 point of drained max hp
heal wounds:
	heals 10 - 38
	if at full hp: restore 2-7 point of drained max hp
speed:
	hastes for 39 + d(power)
might: 
	adds 5 might for duration: 34 + d(power), with max. 80
gain xxx:
	adds corresponding mutation (1 level = 1 point per potion)
levitation:
	adds levitation duration 24 + d(power), max 100
invisibility:
	turn invis. for 14 + d(power), or increase duration with d(power); max = 100
porridge:
	lessen hunger by 6000 (almost half the maximum)
degeneration:
	lose 1-5 points from random stat
restore abilities:
	restores all stats to full
berserk:
	Str +5, hp x 1.5 (up to max), haste. When ends: might pass out for d4 turns, slowed for 12+2d12 turns, hunger - 700. Duration: 19+d20

cure mutation:
	cures 1-8 mutations at random (on average 5.2)

poison:
	no effect if poison resistant; else poison level + 1-6 
poison, strong poison:
	no effect if poison resistant; else poison level + 3-16
slowing:
	slowed for 9 + d(power)
paralysis:
	held for 1 + d6 turns (if cumulative: max = 13)
confusion:
	confused for 2 + d8 turns
mutation:
	adds 4 random mutations


not randomly generated:
decay:
	rots for 9 + d10 points
water:
	lessens hunger by 20 (= close to nothing)
experience:
	gains 2 levels (?)
magic:
	adds 5-24 max magic points, or a quarter of that for points above 50