-delete! is now a regular method that takes a fact and removes it
-this simplifies reading and deletion storage (no `eval` needed)
-fid is now more descriptively called fact-id
-by default, fact-bases now have the three single-level indices active
-Added option for :abc index
-Renamed write-diff! to write-delta! (more accurate)
-Removed default settings from fact-base class declaration
-updated make-fact-base with an :id arg
-Changed load! to call make-fact-base rather than make-instance directly
-Added new-id to generate keyword ids