Fixed Current type in KeyEnumerator

Changed return type of the Current property from "JSONNode" to "string".

Author: Bunny83

SimpleJSON.cs

@@ -199,7 +199,7 @@ public struct KeyEnumerator
             public KeyEnumerator(List<JSONNode>.Enumerator aArrayEnum) : this(new Enumerator(aArrayEnum)) { }
             public KeyEnumerator(Dictionary<string, JSONNode>.Enumerator aDictEnum) : this(new Enumerator(aDictEnum)) { }
             public KeyEnumerator(Enumerator aEnumerator) { m_Enumerator = aEnumerator; }
-            public JSONNode Current { get { return m_Enumerator.Current.Key; } }
+            public string Current { get { return m_Enumerator.Current.Key; } }
             public bool MoveNext() { return m_Enumerator.MoveNext(); }
             public KeyEnumerator GetEnumerator() { return this; }
         }