Expansion of testing suite to cover incl. library

Expands the testing suite to verify behavior of provided library
functions. Updates the README further for clarification on important
concepts.

src/REPL.hs

@@ -28,7 +28,7 @@ repl env = runInputT defaultSettings (loop env)
           case Map.lookup "__result" newEnv of
             Just r -> do
               outputStrLn $ "tricu > " ++ show r
-              outputStrLn $ "DECODE -: " ++ decodeResult r
+              outputStrLn $ "DECODE -: \"" ++ decodeResult r ++ "\""
             Nothing -> return ()
           loop newEnv
 
@@ -36,7 +36,7 @@ decodeResult :: T -> String
 decodeResult tc = case toNumber tc of
   Right num -> show num
   Left _ -> case toString tc of
-    Right str -> "\"" ++ str ++ "\""
+    Right str -> str
     Left _ -> case toList tc of
       Right list -> "[" ++ intercalate ", " (map decodeResult list) ++ "]"
       Left _ -> ""