Feature request: Named Slots (Named child)

[IanLuan]

It would be great if we could have named slots. For slippers consistency, I think the best option would be something like:

<!-- card.html -->
<div class="card">
  <div class="card-title"> {{ children.title }} </div>
  <div class="card-action"> {{ children.action }} </div>
</div>

<!-- index.html -->
{% #card %}
  {% child title %}
    <span>My Title</span>
  {% endchild %}

 {% child action %}
    <button>My action</button>
  {% endchild %}
{% /card %}

It would also be possible to use only children:

<!-- card.html -->
<div class="card">
  {{ children }}
</div>

If approved, I can create a pull request for it.