Make timers yield self when triggered and make repeating timers cancellable

lib/cyberarm_engine/timer.rb

@@ -16,10 +16,15 @@ module CyberarmEngine
         @last_interval = Gosu.milliseconds
         @triggered = true
 
-        @block.call if @block
+        @block.call(self) if @block
       end
     end
 
+    def cancel
+      @looping = false
+      @triggered = true
+    end
+
     def dead?
       @triggered && !@looping
     end