calibrate.py should now work.

A bunch of changes in one commit, sorry.

Moved to fledgling splittable_kwargs system to make default argument
maintenance easier.  I expect the splittable_kwargs system still has
some growing to do, but it's already better than the old system.

Merged BE database from the calibcant subdir into the main BE database.
It was a mistake to create the database there in the first place.