Use vsync, we don't like the tearing.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3536 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/jme/JmeApp.java

@@ -211,6 +211,7 @@ public class JmeApp
             _properties.getWidth(), _properties.getHeight(),
             _properties.getDepth(), _properties.getFreq(),
             _properties.getFullscreen());
+        _display.setVSyncEnabled(true);
 
         // create a camera
         float width = _display.getWidth(), height = _display.getHeight();