Add collapsible open/close events

[drub0y]

Main work here is surfacing the open/close events from the Materialize collapsible component in friendly ways for the Aurelia developer. The developer can hook these events in one of two ways:

1. Using the .call expression in the attribute to directly bind a function call on their view model via the new onOpen and onClose properties (note: on-open and on-close in attribute syntax!).
2. Via the EventAggregator infrastructure where two new events are published in the form of: aurelia-md-bridge:collapsible:[open|close]. I would especially like feedback on whether or not you guys want the framework to be publishing via EventAggregator and, if so, if you "like" the naming scheme I've chosen.

NOTE: this also adds a new sample for the Collapsible component from this gist to demonstrate how both approaches could be used to the caller. If you think these should be broken up into two different samples I can certainly do that.

Ancillary work included here just updates some project level settings to make the project more friendly to work with (at least from VSCode). Details in commit message for 669e8db should be pretty straightfwd so I won't repeat them here.

[Thanood]

Thanks a lot, @drub0y! 👍

I'm a little unsure about the event aggregator. When users subscribe to onClose/onOpen they could fire their own global events from there, right?

[drub0y]

Yes, they could. It's really just a question of whether the component itself offers multi-cast style eventing via the EventAggregator or not. If nothing else in the bridge is doing this (or planning on adding it) then, I agree, it doesn't make sense for this one component to do it. If anything you'd want to offer events throughout the entire framework for a consistent development experience.

[drub0y]

I ripped out the EventAggregator support, simplified the implementation and sample.

[Thanood]

Thanks a lot!
I really like the sample, too. 😃

Maybe I should have told you before.. We have some commit message conventions which simplify changelog generation.. Would you mind squashing commits and change the commit message to (for instance) "feat(md-collapsible): add onOpen/Close event support"?

Sorry for mentioning it so late. 😃
If you want, we can skip it this time and I'll change it after merging, no problem.

[drub0y]

Done!

[Thanood]

Thank you, sir! 😃

[Thanood]

Released and published in 0.22.0.