- Add methods to registry that do the lion's share of the various jobs
  currently performed by ZCML directives.  Change existing ZCML
  directives to use these methods of the registry.

- Emit a set of events at startup that calls an event listener with
  the registry before and after ZCML parsing.

- Make ZCML filename argument optional to ``make_app``.  Document
  configuration without ZCML.

- Replace martian with something simpler.