add reference package (#307)

Author: Cokemonkey11

wurst/_handles/primitives/Reference.wurst

@@ -0,0 +1,18 @@
+package Reference
+/**
+    A simple wrapper class which contains a reference to a value of the given type.
+	The main usage is to wrap primitives to modify them inside closures.
+	
+	> 	let dist_ref = new Reference(0.)
+	>	someList.for_each() (real elem) ->
+	>		if dist_ref.val < 500	
+	>			dist_ref.val += elem
+	
+	Make sure to destroy references if you don't need them anymore.
+*/
+
+public class Reference<T:>
+    T val
+
+    construct(T val)
+        this.val = val