add more :extends values for rules.
put header in <h2> and hide it from tablized display.
-fix treatment of values of type Clojure.lang.Cons: treat the same as other lists
new (show-lexicon) display function, platform for experimenting with lexicon search UI
fix bug: had to do fs/copy before unify.
moving semantic implicature (e.g. human -> not edible) to generation-time (out of lexical entries themselves)
-add (random-extend) to choose a random rule for given phrasal parent.

-temporarily move (random-sentence) to simpler version until new generate is working.
-add vp-past as a rule
-fix :extend typos
display of :extend feature.
more usage notes and examples.
show ellipses (..) if content is not visible (e.g. italian or english is underspecified)
handle regular past for -ere, -are, and -ire verbs.