Allow the current alpha value to be obtained.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3428 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/media/effects/FadeEffect.java

@@ -52,6 +52,11 @@ public class FadeEffect
             (_alpha >= _target) : (_alpha <= _target);
     }
 
+    public float getAlpha ()
+    {
+        return _alpha;
+    }
+
     public boolean tick (long tickStamp)
     {
         // figure out the current alpha