updating version

Changed to beta

Babylon/babylon.engine.ts

@@ -462,7 +462,7 @@
         }
 
         public static get Version(): string {
-            return "2.1.0 alpha";
+            return "2.1.0 beta";
         }
 
         // Updatable statics so stick with vars here
@@ -2261,4 +2261,4 @@
             }
         }
     }
-}
+}