Addint an existing timer event now updates the type and trigger time(s)

Before: Did not add or update the event
stringToStructTranslator_thr now forwards non-string messages
Elevator driver currFloor default set to -1
Event loop works with a single elevator. No init.
Elevator interface/classes changed back to runtime checking (due to polymorphism-template interaction bug)

Cannot instantiate templates in an interface, because the interface functions are never generated (because it's an interface...)