Register a function on this event
Functions are run in registration order
An optional string argument can be given, grouping functions under that name, for an easier management later on
overload 1:
Event:register(func)
| Method Property | Fluent Description | Representation |
| func accepts | a function | |
| Return Value | an Event | |
overload 2:
Event:register(func, name)
| Method Property | Fluent Description | Representation |
| func accepts | a function | |
| name accepts | a String | |
| Return Value | an Event | |