First checkpoint for repetition refactor

This begins the refactor of Repetition for the new bindings and
collections.

The following works:

-   A dummy controller that just reflects an objects array on the
    controlled visibleObjects array.
-   A simple list with adding and removing iterations in response to
    changes to the data model.
-   Draw cycle.
-   objectAtCurrentIteration bindings.

This leaves the following important work yet to be done:

-   Test for nested repetitions.
-   Support selection management.
-   Refactor controllers.
-   Refactor flow.