tidy: del unused Eq, add custom Show

Logic/Statement/Serialize.hs

@@ -10,28 +10,28 @@ data TokenString = TokenString
   { tsCanEval :: CanEval
   , tsLevel :: Int
   , tsString :: String
-  } deriving (Show, Eq)
+  } deriving Show
 
 data CanEval
   = Filler
   | CanEval
-  deriving (Show, Eq)
+  deriving Show
 
 data TokenValue = TokenValue
   { tvLevel :: Int
   , tvValue :: Value
-  } deriving (Show, Eq)
+  } deriving Show
 
 data Value
   = NoValue
   | Value Bool
-  deriving (Show, Eq)
+  deriving Show
 
 data SerializeFormat
   = Plain
   | Latex
 --  | PrefixPlain
-  deriving (Show, Eq)
+  deriving Show
 
 serialize :: SerializeFormat -> Statement -> String
 serialize fmt s = concat $ map tsString $ serializeStrings fmt s