WIP: use newer API

[shashi]

in an attempt to get this to work, I have removed the mention of show_cb thing.

I removed some of the explicit SystemJS code, and the callback and dependencies kwargs, as it turns out you can now add them after the Widget object has been created (but before it gets rendered). Thanks to vue now returning the widget object!

Demo:

[shashi]

I see Vue.component("vue-slider", VueSlider) is required to be run before Vue instance is created but after vue has been loaded... I thought of wrapping the vue widget with another widget which sets up the component but then you'd have to have it forward all the observables as well... So I think it's easiest to bring this one back!

[shashi]

Oh wait, there's a beforeCreate lifecycle handler :D

[shashi]

@JobJob solved the hooking in issue by delaying creating the vue instance till the next event loop tick!

Now this WORKS! --

using Vue

function slider(rng)
    w = vue(dom"div"(
        dom"vue-slider[ref=slider, v-model=value]"()
      ), ["value" => Observable{Any}(first(rng))]
    )
    on(identity, w["value"])
    import!(w, "https://nightcatsama.github.io/vue-slider-component/dist/index.js")
    onimport(w, @js function (Vue, vueSlider)
            Vue.component("vue-slider", vueSlider)

    end)
    w
end