Omigosh, let's capture any errors thrown while unloading media.

I was pretty sure the event handlers did this, but Annie sent me a trace
that would seem to indicate otherwise.


git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@573 ed5b42cb-e716-0410-a449-f6a68f950b19

src/as/com/threerings/flash/MediaContainer.as

@@ -333,7 +333,11 @@ public class MediaContainer extends Sprite
                 } catch (ioe :IOError) {
                     // ignore
                 }
-                loader.unload();
+                try {
+                    loader.unload();
+                } catch (e :Error) {
+                    // ignore
+                }
                 dispatchEvent(new Event(Event.UNLOAD));
 
                 removeChild(loader);