Copy cancel state to fake EntityExplodeEvent.

It's not clear if this change actually solves the underlying issue,
because it has not been tested in a controlled environment. However,
considering the EntityExplodeEvent constructor, which doesn't take a
cancel state value, and the `HIGHEST` priority setting of MobArena's
event handler, the issue is realistic, and this change very likely
solves the issue.

Fixes #704

src/main/java/com/garbagemule/MobArena/listeners/MAGlobalListener.java

@@ -203,6 +203,7 @@ public class MAGlobalListener implements Listener
 
         // Account for Spigot's messy extra event
         EntityExplodeEvent fake = new EntityExplodeEvent(null, event.getBlock().getLocation(), blocks, event.getYield());
+        fake.setCancelled(event.isCancelled());
         entityExplode(fake);
 
         // Copy the values over