Magic items now can add to saving throw modifiers, and added

Ankylosaurus back in.

This is all or nothing at the moment, so all saving throws get the
same bonus.

Fixes: https://github.com/canismarko/dungeon-sheets/issues/101

dungeonsheets/monsters/monsters_a.py

@@ -1539,6 +1539,39 @@ class Ankheg(Monster):
     spells = []
 
 
+class Ankylosaurus(Monster):
+    """Thick armor plating covers the body of the plant-eating dinosaur
+    ankylosaurus, which defends itself against predators with a
+    knobbed tail that delivers a devastating strike.
+    
+    Tail
+      *Melee Weapon Attack:* +7 to hit, reach 10 ft., one
+      target. *Hit:* 18 (4d6+4) bludgeoning damage. If the target is a
+      creature, it must succeed on a DC 14 Strength saving throw or be
+      knocked prone.
+
+    """
+    # TODO: This doesn't appear to be SRD
+    name = "Ankylosaurus"
+    description = "Huge beast, unaligned"
+    challenge_rating = 3
+    armor_class = 15
+    skills = ""
+    senses = "passive Perception 11"
+    strength = Ability(19)
+    dexterity = Ability(11)
+    constitution = Ability(15)
+    intelligence = Ability(2)
+    wisdom = Ability(12)
+    charisma = Ability(5)
+    speed = 30
+    swim_speed = 0
+    fly_speed = 0
+    climb_speed = 0
+    hp_max = 68
+    hit_dice = "8d12+16"    
+
+
 class Ape(Monster):
     """
     Multiattack.