Added extended script action zone properties

lib/Properties.hs

@@ -499,6 +499,17 @@ checkTileLayerProperty p@(Property name _value) = case name of
       isString p
       requireProperty "bellVariable"
 
+    -- | these properties are used by the extended script to allow action zones¶
+    "bindVariable" -> do
+      isString p
+      requireProperty "zone"
+    "enterValue" -> do
+      isString p
+      requireProperty "bindVariable"
+    "leaveValue" -> do
+      isString p
+      requireProperty "bindVariable"
+
 
     -- name on tile layer unsupported
     "name" -> isUnsupported