Added language support to main menu and sign

assets/en.json

@@ -1,7 +1,16 @@
 {
-  "general": {
-    "test": {
-      "test": "test"
+  "main_menu": {
+    "new_game": "New Game",
+    "load_game": "Load Game",
+    "options": "Options",
+    "exit": "Exit"
+  },
+  "maps": {
+    "testmap": {
+      "sign": {
+        "text": "This is a sign.",
+        "name": "Sign"
+      }
     }
   }
 }

assets/testmap.json

@@ -40,7 +40,7 @@
       "type": 3,
       "x": 3,
       "y": 8,
-      "text": "This is a sign."
+      "text": "maps.testmap.sign"
     },
     {
       "type": 4,