add event type

[ofhope]

Casting event param to Event type rather than string. This offers stricter parameter checking avoiding fat fingering and code completion.

[goto-bus-stop]

Thanks for the PR! I'd really like to do this, but I'm not sure if we can. Plugins can add new event types, some of which are user-facing too (like dashboard:modal-closed).

We could do it now by adding like all the plugin event names to this list, but it should be user-extensible so third party plugins can also work :/

[ofhope]

Ahhh yeah I didn't think about plugins potentially creating their own.
We can add string type to the end of the event type. This wouldn't be any different to it is now but would offer code completion in a TS environment.

Heres an example
http://www.typescriptlang.org/play/?ssl=3&ssc=24&pln=3&pc=46#code/C4TwDgpgBAyg9gWwgUQG4QHbCgXigIgGMAbAS0IGt8oAfAgI2IFcAnaugZ2BdIwHMA3ACghhOBi5QAZnDgAueEjSZsefABMAhhwAW9OJpbq5COFuIBaEnA4R1+YWInZ6hhYhTosuAiXJVhISA

Alternatively for pure JS I was wondering about defining a constant hash for events. Personally I find it easier to read. Also simplifies renaming of events, and centralises events in one place hopefully making it more self documenting.

const Event = {
   CANCEL_ALL: "cancel-all"
}

this.emit(Event.CANCEL_ALL)

[goto-bus-stop]

Autocomplete is an interesting point, I didn't think of that as i don't have it set up 🙃

if you would like to add the | string variant to this PR, we would be good to go 👍

[ofhope]

Done. I had to add do some additional typing to get intellisense to work.
It doesn't work as intuitively as I'd thought, you can't just make union type of string :(
Some discussion about it here
microsoft/TypeScript#29729 (comment)

Also trimmed down the verbosity of TS tests since we're accepting string I only tested a few main event types and custom events.

[goto-bus-stop]

merci merci!