Expose the Index type

[DavidDTA]

Currently is is not possible to

import Material.Component

or to reference the type Material.Component.Index.

Since this is in the signature of many library methods (render, etc.), I would like to refer to this type in order to make my method signatures cleaner.

For example, I would like to say

renderSubcomponent : Material.Component.Index -> Html a
renderSubcomponent = ...

but instead must use

renderSubcomponent : List Int -> Html a
renderSubcomponent = ...

which is much less clear.