Allowing other plugins to disable PvP protections.

Now plugins that want to can selectively disable GP's PvP protections.

src/me/ryanhamshire/GriefPrevention/events/PreventPvPEvent.java

@@ -0,0 +1,49 @@
+package me.ryanhamshire.GriefPrevention.events;
+
+import me.ryanhamshire.GriefPrevention.Claim;
+
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+
+//if cancelled, GriefPrevention will not cancel the PvP event it's processing.
+public class PreventPvPEvent extends Event implements Cancellable
+{
+    private static final HandlerList handlers = new HandlerList();
+    private boolean cancelled = false;
+
+    public static HandlerList getHandlerList()
+    {
+        return handlers;
+    }
+
+    Claim claim;
+
+    public PreventPvPEvent(Claim claim)
+    {
+        this.claim = claim;
+    }
+
+    public Claim getClaim()
+    {
+        return this.claim;
+    }
+
+    @Override
+    public HandlerList getHandlers()
+    {
+        return handlers;
+    }
+    
+    @Override
+    public boolean isCancelled()
+    {
+        return this.cancelled;
+    }
+    
+    @Override
+    public void setCancelled(boolean cancelled)
+    {
+        this.cancelled = cancelled;
+    }
+}