SL Backcompat Plan:

*** 0.04006 mode

* add a loud warning that says that we're running in backcompat mode, and refers
  to the ::Manual::UpgradingFromV4 POD.
* preserve custom content from un-singularized Results and delete them when in
  upgrade mode

*** backcompat tests

Need a comprehensive backcompat.t

*** Catalyst Helper

* Add 'upgrade=1' option that upgrades from both old S::L and old helper,
  whichever or both.
* Warn when old helper output or 0.04000 S::L output is detected, that refers to
  the upgrade option.

Release dev S::L, announce to catalyst, dbic lists and #catalyst that testing of
backcompat mode is needed, wait 2-3 weeks, then release 0.05000.