Fix WECUI not working for players when rejoining the server. Closes #196.

src/main/java/com/sk89q/worldedit/bukkit/CUIChannelListener.java

@@ -39,7 +39,7 @@ public class CUIChannelListener implements PluginMessageListener {
     @Override
     public void onPluginMessageReceived(String channel, Player player, byte[] message) {
         LocalSession session = plugin.getSession(player);
-        if (session.hasCUISupport()) { // Already initialized
+        if (session.hasCUISupport() && plugin.hasPluginChannelCUI(player.getName())) { // Already initialized
             return;
         }
 

src/main/java/com/sk89q/worldedit/bukkit/WorldEditPlugin.java

@@ -25,7 +25,9 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Map;
+import java.util.Set;
 import java.util.jar.JarFile;
 import java.util.zip.ZipEntry;
 
@@ -73,7 +75,7 @@ public class WorldEditPlugin extends JavaPlugin {
     /**
      * Stores players who are using plugin channels for the cui
      */
-    private final Map<String, Boolean> pluginChannelCui = new HashMap<String, Boolean>();
+    private final Set<String> pluginChannelCui = new HashSet<String>();
 
     /**
      * Called on plugin enable.
@@ -391,15 +393,14 @@ public class WorldEditPlugin extends JavaPlugin {
     }
 
     public void setPluginChannelCUI(String name, boolean value) {
-        pluginChannelCui.put(name, value);
+        if (value) {
+            pluginChannelCui.add(name);
+        } else {
+            pluginChannelCui.remove(name);
+        }
     }
 
     public boolean hasPluginChannelCUI(String name) {
-        Boolean val = pluginChannelCui.get(name);
-        if (val == null) {
-            return false;
-        } else {
-            return val;
-        }
+        return pluginChannelCui.contains(name);
     }
 }