Various enhancements for RC2
1) Re-introduce unmapAll() and mapCommand() as deprecated methods that pass-through to their new destroy() and wireCommand() counterparts, with optional deprecation warnings written to the console if used.
2) If a singleton has an initialize() method, automatically wrap it with a pre-initialize function that injects its wirings.  Useful for Models with wiring dependencies in their initialize() method.
3) Allow custom wirings to be specified in the Context's wirings map