Adding buttons field to mouse events

[kdillon]

Syn does not properly fill the "buttons" field in mouse-type event generation. This change adds 'buttons' for most mouse-events (but not for jQuery drag & drop - in this case it adds "undef" buttons - for some reason that I have yet to understand, setting the buttons field in jQuery will prevent the drag)

The size of this change is a bit worrisome. I feel like the size of this change is an indication that the way FuncUnit / Syn is organized should be revisited. It probably shouldn't require so many far-flung changes to add a field in the mouse event generation.

Now that we've dropped support for IE, we could look at some more ES6-style workflows, maybe use the event constructors rather than using the initializer, and create them directly rather than via the event trigger (which shaves off a lot of useful data that we need to re-find).

It could also be helpful to make Syn/FuncUnit stateful. Rather than interrogate and try and keep track of which buttons are down, we could have a global state machine that describes the "current state" of user interactions. (which buttons are down, keys, etc)

[justinbmeyer]

Thanks. I just did a big rewrite. I organized the events like:

dragstart = {
  setup(){ .. }    // do this before the event
  options(){ .. }   // create options
  create() { .. }   // create the event
  default() { .. }   // default actions
}

This should make it easier to make changes like this.

I'm going to try to pull this in to these changes.