SPIGOT-1111: Fix ServerCommandEvent not being cancelled.

nms-patches/DedicatedServer.patch

@@ -162,7 +162,7 @@
          super.B();
          this.aO();
      }
-@@ -296,7 +362,14 @@
+@@ -296,7 +362,15 @@
          while (!this.l.isEmpty()) {
              ServerCommand servercommand = (ServerCommand) this.l.remove(0);
  
@@ -170,6 +170,7 @@
 +            // CraftBukkit start - ServerCommand for preprocessing
 +            ServerCommandEvent event = new ServerCommandEvent(console, servercommand.command);
 +            server.getPluginManager().callEvent(event);
++            if (event.isCancelled()) continue;
 +            servercommand = new ServerCommand(event.getCommand(), servercommand.source);
 +
 +            // this.getCommandHandler().a(servercommand.source, servercommand.command); // Called in dispatchServerCommand
@@ -178,7 +179,7 @@
          }
  
      }
-@@ -491,13 +564,60 @@
+@@ -491,13 +565,60 @@
      }
  
      public String getPlugins() {