Fix some compiler errors caused by my recent commits... which is

what I get for doing some 'harmless' cleanup without rebuilding before
commit...

Author: pspeed42

src/main/java/com/simsilica/ethereal/zone/StateBlock.java

@@ -36,6 +36,7 @@
 
 package com.simsilica.ethereal.zone;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import com.simsilica.mathd.Quatd;

src/main/java/com/simsilica/ethereal/zone/Zone.java

@@ -109,7 +109,7 @@ public final boolean isEmpty() {
      */   
     public boolean commitUpdate() {
         if( log.isTraceEnabled() ) {
-            log.trace(log.info(key + ":commitUpdate() empty:" + current.isEmpty() + "   children:" + children);
+            log.trace(key + ":commitUpdate() empty:" + current.isEmpty() + "   children:" + children);
         }
         if( current.isEmpty() ) {
             // Return true if history is not empty... false otherwise.