Use menus for combat and picking up items

Refactor a bunch of stuff around to allow for polymorphically surfacing
an EntityChar for all entities, and use this to write a generic
`entityMenu` function, which generates a menu from the chars of a list
of entities - and use that to fully implement (removing `undefined`)
menus for both attacking and picking things up when there are multiple
entities on the relevant tile.

test/Xanthous/Data/EntityCharSpec.hs

@@ -1,20 +1,18 @@
 --------------------------------------------------------------------------------
-module Xanthous.EntitiesSpec where
+module Xanthous.Data.EntityCharSpec where
 --------------------------------------------------------------------------------
 import           Test.Prelude
 --------------------------------------------------------------------------------
 import qualified Data.Aeson as JSON
 --------------------------------------------------------------------------------
-import           Xanthous.Entities
+import           Xanthous.Data.EntityChar
 --------------------------------------------------------------------------------
 
 main :: IO ()
 main = defaultMain test
 
 test :: TestTree
-test = testGroup "Xanthous.Entities"
-  [ testGroup "EntityChar"
-    [ testProperty "JSON round-trip" $ \(ec :: EntityChar) ->
-        JSON.decode (JSON.encode ec) === Just ec
-    ]
+test = testGroup "Xanthous.Data.EntityChar"
+  [ testProperty "JSON round-trip" $ \(ec :: EntityChar) ->
+      JSON.decode (JSON.encode ec) === Just ec
   ]

test/Xanthous/GameSpec.hs

@@ -2,10 +2,10 @@ module Xanthous.GameSpec where
 
 import Test.Prelude hiding (Down)
 import Xanthous.Game
+import Xanthous.Game.State
 import Control.Lens.Properties
 import Xanthous.Data (move, Direction(Down))
 import Xanthous.Data.EntityMap (atPosition)
-import Xanthous.Entities (SomeEntity(SomeEntity))
 
 main :: IO ()
 main = defaultMain test