Major updates to core definitions.
Major updates to core definitions.

-- No bounds on exponent (Harrison); allowed
   exp to be integer
-- normal/denormal no longer relevant for now
-- removed unneeded phase defns
-- no `largest' fp number for now
-- added prev/next/floor/ceil fp number defns
-- updated ulp defn to work for arbitrary real nums

soarlab/FPTaylor,soarlab/FPTaylor,soarlab/FPTaylor,soarlab/FPTaylor