Use act() in reactor scripts where possible, provide empty act() otherwise

"function hit()" has triggered on each reactor hit,
while "function act()" is only triggered once it's destroyed or reached an end state

scripts/reactor/2618000.js

@@ -40,4 +40,6 @@ function hit() {
             rm.getMap().getReactorByName(reactname).hitReactor(rm.getClient());
         }
     }
-}
+}
+
+function act() {}