Views only have an immediate onViewRendered cb

You don’t get the “wait for attached” behavior from Blaze.View anymore, you just get a plain onViewRendered callback.  No onMaterialized.  The template “rendered” callback implements the wait-for-attached and wait-for-afterFlush parts.

Also, if a template somehow re-renders, it won’t get extra event handlers now.  And if it re-renders before being attached, something sensible will happen (like all the calls of the rendered callback will be saved for onAttached).

view.isCreatedForExpansion and view.isInRender become private.