Move eStatus handling into the setStatusCallback routine and deprecate the setEStatusCallback.  The underlying code hasn't been fixed to unify things and the sysstatus support is not present yet.
Remove access to setEStatusMainCallback which was intended to be a library internal access point.  At least changing these will break the library.

This whole mention needs a rethink to allow multiple status callbacks on one status event.
Reload the RTC from the display on init events.
Localise some functions.
Clean up status callbacks better on shutdown.
Modify the setpoint and IO infrastructure to use a common implementation and to dispatch to this rather than duplicating chunks of the same code.