Return value of Deque#pop could be null.

As explained by the old doc, "If block is false and the deque is empty, the function returns null immediately." (http://haxe.org/api/neko/vm/deque)

std/cpp/vm/Deque.hx

@@ -33,7 +33,7 @@ class Deque<T> {
 	public function push( i : T ) {
 		untyped __global__.__hxcpp_deque_push(q,i);
 	}
-	public function pop( block : Bool ) : T {
+	public function pop( block : Bool ) : Null<T> {
 		return untyped __global__.__hxcpp_deque_pop(q,block);
 	}
 }

std/neko/vm/Deque.hx

@@ -32,7 +32,7 @@ class Deque<T> {
 	public function push( i : T ) {
 		deque_push(q,i);
 	}
-	public function pop( block : Bool ) : T {
+	public function pop( block : Bool ) : Null<T> {
 		return deque_pop(q,block);
 	}
 	static var deque_create = neko.Lib.loadLazy("std","deque_create",0);