Amber config used

This configures amber to use `amber config`. Loader does not load `amber.js` any more.
`amber config` generates it.

I did not commit it yet, as it is easy to add it if decided so, for the time being I kept  VCS clean.

Manfred Kröhnert wrote:
> In internal/index.html:
>
> >       <script type='text/javascript'  src='../support/requirejs/require.min.js'></script>
> >  +<script type='text/javascript'  src='../config.js'></script>
>
> @herby <https://github.com/herby> the |config.js| script seems to be 
> missing in the branch.
>
> —
> Reply to this email directly or view it on GitHub 
> <https://github.com/amber-smalltalk/amber/pull/1035/files#r14062221>.
>