Big Arena improvments, including UI

game/engines/default/engine/ai/simple.lua

game/modules/tome/ai/shadow.lua

game/modules/tome/ai/tactical.lua

game/modules/tome/class/NPC.lua

game/modules/tome/class/generator/actor/Arena.lua

game/modules/tome/class/uiset/Minimalist.lua

game/modules/tome/data/chats/arena-start.lua

game/modules/tome/data/chats/arena.lua

game/modules/tome/data/damage_types.lua

game/modules/tome/data/general/events/cultists.lua

game/modules/tome/data/general/npcs/ant.lua

game/modules/tome/data/general/npcs/aquatic_critter.lua

game/modules/tome/data/general/npcs/aquatic_demon.lua

game/modules/tome/data/general/npcs/bear.lua

game/modules/tome/data/general/npcs/bird.lua

game/modules/tome/data/general/npcs/bone-giant.lua

game/modules/tome/data/general/npcs/canine.lua

game/modules/tome/data/general/npcs/cold-drake.lua

game/modules/tome/data/general/npcs/construct.lua

game/modules/tome/data/general/npcs/elven-caster.lua