QueueThing: add ability to request a specific item for processing.

src/main/java/moe/nekojimi/chords/QueueThing.java

@@ -74,6 +74,18 @@ public abstract class QueueThing<I, O> implements Consumer<I>
         }
     }
 
+    public List<Promise<I, O>> requestSpecific(List<I> inputs, Consumer<O> destination)
+    {
+        List<Promise<I, O>> ret = new ArrayList<>();
+        for (I input : inputs)
+        {
+            Promise<I, O> promise = new Promise<>(input, destination);
+            ret.add(promise);
+            handlePromise(promise);
+        }
+        return ret;
+    }
+
     public List<Promise<I, O>> request(int count, Consumer<O> destination)
     {
         List<Promise<I, O>> ret = new ArrayList<>();