Feature/103 improve events (#201)

* Improve event handler to only run events that have been registered

* Tidy up events into their own function files

src/contracts/IEventItem.ts

@@ -1,6 +1,7 @@
 
-import { Event } from "../type/event";
+import { EventType } from "../constants/EventType";
 
 export default interface IEventItem {
-    Event: Event,
+    EventType: EventType,
+    ExecutionFunction: Function,
 }